EP0344185B1 - Redundant robot - Google Patents

Redundant robot Download PDF

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Publication number
EP0344185B1
EP0344185B1 EP88901269A EP88901269A EP0344185B1 EP 0344185 B1 EP0344185 B1 EP 0344185B1 EP 88901269 A EP88901269 A EP 88901269A EP 88901269 A EP88901269 A EP 88901269A EP 0344185 B1 EP0344185 B1 EP 0344185B1
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EP
European Patent Office
Prior art keywords
robot
stage
platform
actuators
configuration
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP88901269A
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German (de)
French (fr)
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EP0344185A1 (en
Inventor
Ameur Ch'hayder
Didier Durand
Constantino Diaz
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Logabex Sarl
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Logabex Sarl
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Publication date
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Priority to AT88901269T priority Critical patent/ATE67710T1/en
Publication of EP0344185A1 publication Critical patent/EP0344185A1/en
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Publication of EP0344185B1 publication Critical patent/EP0344185B1/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q1/00—Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members
    • B23Q1/25—Movable or adjustable work or tool supports
    • B23Q1/44—Movable or adjustable work or tool supports using particular mechanisms
    • B23Q1/50—Movable or adjustable work or tool supports using particular mechanisms with rotating pairs only, the rotating pairs being the first two elements of the mechanism
    • B23Q1/54—Movable or adjustable work or tool supports using particular mechanisms with rotating pairs only, the rotating pairs being the first two elements of the mechanism two rotating pairs only
    • B23Q1/545—Movable or adjustable work or tool supports using particular mechanisms with rotating pairs only, the rotating pairs being the first two elements of the mechanism two rotating pairs only comprising spherical surfaces
    • B23Q1/5462—Movable or adjustable work or tool supports using particular mechanisms with rotating pairs only, the rotating pairs being the first two elements of the mechanism two rotating pairs only comprising spherical surfaces with one supplementary sliding pair
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J17/00—Joints
    • B25J17/02—Wrist joints
    • B25J17/0208—Compliance devices
    • B25J17/0216—Compliance devices comprising a stewart mechanism
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J19/00—Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection with manipulators
    • B25J19/0025—Means for supplying energy to the end effector
    • B25J19/0029—Means for supplying energy to the end effector arranged within the different robot elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/06—Programme-controlled manipulators characterised by multi-articulated arms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/08—Programme-controlled manipulators characterised by modular constructions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1615—Programme controls characterised by special kind of manipulator, e.g. planar, scara, gantry, cantilever, space, closed chain, passive/active joints and tendon driven manipulators
    • B25J9/1623—Parallel manipulator, Stewart platform, links are attached to a common base and to a common platform, plate which is moved parallel to the base
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/40—Robotics, robotics mapping to robotics vision
    • G05B2219/40277—Hybrid, connect parallel manipulators in series, Stewart truss

Definitions

  • the invention relates to a redundant robot of the modular type, making it possible to move a terminal from an initial situation to a final situation.
  • the oldest robots called industrial robots, have a mechanical architecture made up of bodies or links linked together so as to allow rotation or translation of a link relative to the neighboring links.
  • the links are generally different from each other in order to specialize the robot for a given type of task.
  • the essential defect of these robots lies in their complex and costly mechanics, and in their very high mass in relation to the payload that can be moved, this essentially due to the working conditions for bending and twisting of the constituent elements of these robots.
  • these robots are not redundant and are therefore unable to function properly in the event of the failure of one or more mobilities.
  • redundant robots have been designed more recently to intervene in congested or almost closed environments.
  • redundant robot is meant a robot having a number of mobilities that is overabundant in relation to the number of mobilities necessary and sufficient to position and orient a terminal in space. Their redundant number of mobilities make it possible to ensure positioning and orientation of the terminal in several different ways, so that these robots benefit from a much greater flexibility of use than the previous ones.
  • the present invention proposes to provide an advanced robot of the above-mentioned redundant type, provided with a control making it possible to exploit all its potentials.
  • robot is meant an articulated mechanical system constituted by a sequence of at least two stages, with which is associated a control unit.
  • control unit constituted by a sequence of at least two stages, with which is associated a control unit.
  • Another essential objective is to provide a robot benefiting from a large number of mobilities, allowing it to intervene in congested environments thanks to the choice of a suitable path among a large number of possible paths.
  • An essential objective of the invention is to allow the handling of high loads, and to benefit from a charge / mass ratio of the robot, of increased value compared to known robots.
  • Another objective is to provide a robot with good fault tolerance, that is to say capable of performing a task even in the event of failure of certain elements.
  • Another objective is to provide a mechanically simple robot, the stages of which can be repeated, either identically or with dimensional modifications, each stage itself being made up of repetitive elements.
  • Another objective is to provide a modular robot, expandable at will according to the type of task to be accomplished.
  • Another objective is to provide an easy-to-troubleshoot robot due to the simplicity of its structure and the small variety of components that constitute it.
  • the robot targeted by the invention making it possible to move a terminal from an initial situation to a final situation, is of the modular type comprising at least two stages arranged one after the other, including a first stage integral with 'a base and, opposite, a top floor carrying the terminal.
  • terminal is meant any system, active or passive, suitable for the intended application, for example: pliers, tool, camera, etc ...
  • situation is meant a position and / or an orientation in space, of a reference linked to the element considered with respect to a reference reference.
  • module is meant a repetition of stages having the same type of architecture, these stages being able to be rigorously identical or differing by their dimensions (auxiliary stages of different type being able to intervene if necessary between the modular stages like we will see it later).
  • the robot targeted by the invention is of the type in which each stage is composed of a platform and six linear actuators, each articulated, towards one end, on the platform of the stage considered by a type connection ball joint, and towards its opposite end, on the platform of the preceding stage (or on the base for the first stage) by a connection of the same type, these six linear actuators being arranged according to a closed angulated architecture so that two neighboring actuators are articulated in the vicinity of one another on a platform and are, on the contrary, articulated at a distance on the other platform in order to form an angle between them, each stage comprising a system of sensors, adapted to deliver signals representative of the relative situation of the platform of said stage compared to that of the previous stage (or compared to the base for the first stage).
  • linear actuator any electrical, hydraulic, pneumatic device, etc. capable of generating, on command, a translation between its two ends by which this actuator is articulated on the platform of the stage in question and on that of the previous floor.
  • the actuators can in particular be constituted by jacks, screw / nut systems, but also by more complex mechanisms of the compass mechanism, rack type.
  • ball joint type is generally meant any rotary joint capable of allowing at least two rotations of perpendicular axes, and in particular: ball joint (allowing three rotations of concurrent axes), cardan joint (allowing two rotations of concurrent axes), compound link (allowing two rotations of non-concurrent axes).
  • the "operational coordinates" and “generalized coordinates” respectively represent the situation of the terminal with respect to a reference frame of reference, and the situation of the platforms by considering as reference, for each platform, the neighboring platform.
  • robot configuration is meant the set of generalized coordinates of all the stages of the robot, reflecting the general configuration of the robot in space.
  • status information is meant for each actuator control information, representative of the state that said actuator should take.
  • distance is meant the mathematical distance in an n-dimensional space, where n is the number of operational coordinates necessary to represent a situation (in the most general case: three position coordinates and three orientation coordinates).
  • the robot according to the invention thus consists of stages which, by their triangulated architecture, all work in traction / compression, both at the level of the linear actuators and at that of the platforms.
  • the platforms can themselves be constituted by triangulated systems linking the articulation zones of the actuators, so as to radically remove any bending / torsional stress. It is also possible, depending on the application, to provide platforms of different structure (crown, etc.): certain bending / torsion stresses can then locally develop in these platforms, but keep values reduced by compared to those practiced in most known robots.
  • the robot can thus have a light structure, with low deformation under load, capable of handling high masses.
  • the placing in series of at least two stages of structure as defined above leads to a redundancy of mobilities making it possible to obtain a given final situation of the terminal by a multitude of combinations of states of the actuators.
  • the space accessible by the terminal (robot workspace) is reduced but, for a robot made up of at least a few floors , the number of mobilities remains satisfactory.
  • the control unit makes it possible to exploit these mobilities: from a given initial situation, it makes it possible to determine - if this is possible - a configuration corresponding to the final situation to be reached and to calculate the information of corresponding states of the actuators.
  • the configuration is determined from the operational coordinates entered (final situation to be reached) and accessible space data stored in the above-mentioned storage means (these data representing the space accessible by each platform in a reference system linked to the platform of the previous floor).
  • the defined iterative procedure proceeds step by step using for the current step the configuration obtained in the previous step.
  • an initial configuration is used which can either be entirely conventional, or the actual initial configuration of the robot calculated from the signals from the sensors.
  • the use of the mathematical tool constituted by the Jacobian displacement matrix associated with the configuration of the robot allows a simple linearization of the relation linking the operational coordinates and the set of generalized coordinates representative of this configuration.
  • This relation is easy to use to determine, by its generalized coordinates, a new configuration of the robot from the previous known configuration, by logical operations such as inversion of the Jacobian matrix and multiplication by the distance (or a fraction of this- this).
  • the iterative procedure in successive steps allows convergence until obtaining a precision lower than a predetermined deviation.
  • the membership checks carried out in the above-defined iterative process consist in testing whether the situations of the new configuration are accessible or not, that is to say if the calculated situation of each platform is an accessible situation of that -this. If not, the substitution consists of replacing the calculated situation that is not valid with an accessible situation according to a pre-established criterion, in particular proximity.
  • the determination of the terminal situation corresponding to the new configuration is carried out by a simple geometric calculation from all the calculated situations representative of the configuration. This determination calculates the distance for the next iteration step.
  • the means for storing the data of accessible space comprises means of memorization, storing for each architecture of stages a database containing, for each actuator of the stage considered, the minimum and maximum lengths of this actuator and the maximum angles that said actuator can take relative to normal to the two platforms to which said actuator ends.
  • This embodiment has the advantage, on the one hand, of accurately reflecting the possibilities of movement of a stage (conditioned by its technological components), on the other hand, of requiring little memory space, since four enough data per actuator to characterize the accessible space.
  • the calculations made by the configuration calculation means are longer compared to the following solutions.
  • the means for storing the accessible space data comprise means for storing a calculation program containing, for each floor architecture, relations linking the position (x, y, z) of the center of the platform of the floor relative to the neighboring platform and the possible rotation ( ⁇ ) of said platform in all directions of space.
  • the space accessible by each platform is modeled by mathematical relationships linking the data of accessible space.
  • These relationships are contained in the abovementioned calculation program which is previously loaded into the storage means, depending on the architecture of the robot.
  • program is meant both a series of instructions constituting software, and wired circuits capable of executing instructions defined by these circuits. This lighter realization in computation time has the defect of leading to a loss of possibilities of movements due to modeling.
  • the means for storing the data of accessible space comprise means of memorization, storing, for each architecture of stages, a database divided into zones corresponding to nodes of a spatial mesh: each zone contains data representative, on the one hand, of the position of the corresponding node, on the other hand, possible rotations in this node around predetermined directions.
  • the space accessible by each platform (in a reference system linked to the previous platform) is cut out according to a spatial mesh and the situations of the nodes of this mesh are stored beforehand in the storage means, depending on the architecture of the robot. The calculation times then become very short, but the memory space required is much larger than in the previous cases.
  • the means for inputting the operational coordinates representative of the final situation to be achieved may comprise a man / machine interface, adapted to enable the input of coordinates representative of the final spatial position to be reached by the origin of a given linked reference point. to the terminal and / or coordinates representative of the final orientation to be reached by said reference.
  • these input means can take the form of an input keyboard, a touch screen, a screen associated with an electronic pointing pen, a manipulation system associated with a screen, a voice recognition system, etc ...
  • These input means can also include an interface to a means for injecting operational coordinates, stored or calculated elsewhere, with a view to carrying out a task in the absence of an operator.
  • These input means can also include, on the one hand, a remote sensing system adapted to detect a target to be reached, on the other hand, calculation means adapted to deliver from the signals from the remote sensing system, the representative coordinates the spatial position and / or the spatial orientation of the target.
  • the remote sensing system conventional in itself (notably a video camera, magnetic, ultrasonic or infrared sensor system, etc.) can be embedded on the robot or independent of it.
  • each stage of the robot can be constituted according to the following embodiment: the six actuators of each stage are articulated, on the one hand, on the platform of the stage considered in three distinct zones of said platform, d 'on the other hand, on the platform of the previous floor (or on the base for the first floor) in three distinct zones of said platform (or said base); in addition, these six actuators can be identical, the three articulation zones of the actuators on the platform of the stage in question and the three articulation zones of said actuators on the platform of the preceding stage being arranged at vertices of equilateral triangles.
  • the platforms can have various forms, depending on the application. Generally, they will be produced by a hollow triangulated structure, preserving a central passage along the robot in order to accommodate a transmission beam (supply and control of the actuators, transmission of signals from the sensors, possibly, supply and control of a terminal active).
  • one or more platforms may be constituted by a rigid member of elongated shape, the actuators of the stage concerned being articulated on one end of said member, and the actuators of the following stage being articulated on the opposite end of said member.
  • a more threadlike robot is thus obtained, with an increased range for a given number of stages.
  • each auxiliary stage being composed of a platform, two, three or four linear actuators and a complementary number of rigid bars, so as to obtain an angular isostatic structure closed with six sides, having a geometry similar to that of a modular stage.
  • the robot represented by way of example comprises a modular architecture as shown diagrammatically in FIGS. 1 to 5, associated with a control unit whose block diagram is provided in FIG. 7.
  • This robot comprises several superimposed stages such as first stage 1p, current stages 1 i ⁇ 1, 1 i , and last stage 1d.
  • Each stage is essentially formed by a platform 2, by six identical linear actuators such as 3a, 3b, 3c, 3d, 3e and 3f for the current stage and by a set of sensors as shown schematically in 4a, 4b, 4c in FIG. 2 (for the sake of simplification, these sensors have not been shown in FIG. 1).
  • the cylinders of the first stage 1p are coupled to a base 5 which can be formed by a platform 5a fixed on a base 5b.
  • the platform 6 of the last stage 1d carries a terminal 7 adapted to the task to be performed (clamp in the example shown, possibly associated with a remote sensing camera).
  • the number of stages is at least equal to 2 and will in practice be of the order of 4 to 12, this modifiable number being adapted to the task to be accomplished.
  • each platform such as 2 consists of three blocks of articulations 8a, 8b, 8c arranged at the vertices of an equilateral triangle and connected by spacers 9a, 9b, 9c arranged in a triangle.
  • Each articulation block is formed by a bent section of beam 10 with an H-shaped section carrying above and below its sole articulation axes such as 11 connected to the cheeks of the beam.
  • Each axis 11 is provided with a spherical part 12 guiding another spherical part 13 integral with the end of the rod of the actuator considered, the assembly 11, 12, 13 forming a ball joint which allows rotation, of a part, around the axis 11, on the other hand, around the longitudinal axis of the actuator rod, finally around a third axis, orthogonal to the other two.
  • the spacers 9a, 9b, 9c are welded between the articulation blocks 8a, 8b, 8c and in the example, formed by beams with rectangular section.
  • each stage is in the example constituted by electric linear actuators of a type known per se, as shown in FIG. 4.
  • Each actuator comprises an electric motor 14 carried by a casing 15 housing a reducer 16 which drives in rotation of a screw 17 housed in a cylindrical extension of the casing 15.
  • the casing 15 is articulated on a platform by means of a ball joint as already described.
  • each actuator comprises a nut 18 engaged with the screw 17 and integral with a sheath 19.
  • This sheath is keyed with the extension of the casing so that it can slide relative to the latter without relative rotation.
  • the end of the sheath 19 is articulated by means of a ball joint as described on the neighboring platform.
  • actuators can be provided (hydraulic cylinders, pneumatic ).
  • the six actuators of a stage are arranged as shown in the figures, according to a closed angulated architecture, so that two neighboring actuators are articulated, for a platform, on the same articulation block and, for the platform neighbor, on two neighboring blocks.
  • the neighboring actuators are positioned head to tail.
  • each actuator has its longitudinal axis
  • springs such as 20 which connect the motors 14 to each other (any other system that may be provided).
  • Each electric actuator is associated with a sensor such as 4a, 4b, 4c, capable of delivering a signal representative of the length of said actuator.
  • these sensors are linear sensors with a resistive track, having a cylindrical body integral with the extension of the casing 15 of the actuator and a movable rod, fixed at its end on a lug integral with the sheath 19 of said actuator.
  • the robot can also be dressed externally with a flexible protection connected to the platforms (for example bellows fixed around the platforms).
  • FIG. 6 is a partial view of a variant stage, in which the preceding ball joints are replaced by universal joints 22.
  • Each universal joint allows rotation around two perpendicular axes.
  • the sheath 19 ′ of the actuator is no longer keyed to the extension of the casing 15 ′ in order to allow the rotation of these two elements.
  • each sensor 4 ′ is integral with a lug which can rotate around the sheath 19 ′.
  • the actuators of a stage are all positioned in the same direction, with their motor in the lower part, in order to lower the center of gravity of the entire robot.
  • each platform consists of two identical plates 37, 38 assembled one on the other by screws and nuts, with centering pins for their relative positioning.
  • the trays shown in the figure have a circular shape.
  • This embodiment allows easier robot modifications. Indeed, this arrangement shows modules constituted by a lower plate, the actuator and sensor system and an upper plate, very easy to add or remove without modifying the actuator fixings.
  • Figure 7 is a block diagram showing the robot control unit, with the symbolized links to the various stages of the robot.
  • the terminal carries a clamp and a D.T.C. (charge transfer device) symbolized at 24.
  • D.T.C. charge transfer device
  • the control unit can be housed in a cabinet which is shown diagrammatically at 23 in FIG. 1 near the base 5.
  • This control unit essentially comprises the following electronic assemblies: means for entering 25 operational coordinates representative of the final situation of the terminal to be reached, means for storing 26 data of space accessible by each platform, means for calculating configuration 27 , state calculation means 28, auxiliary state storage means 29, servo interface 30.
  • the input means 25 are equipped with a man / machine interface 31 which allows direct entry of the operational coordinates of the final situation to be reached: position coordinates of the center of the terminal and orientation coordinates, in a reference trihedron.
  • the input can also operate in remote sensing mode thanks to the camera 24 which delivers a flow of sequenced information to an intermediate processing unit 32 adapted to develop and deliver the operational coordinates mentioned above representative of the final situation to be reached for the terminal.
  • the camera 24 and the processing unit 32 are formed by any remote sensing system of the type known per se, capable of recognizing a target to be reached (mechanical part, etc.), of extracting position and / or position information therefrom. orientation and to deliver an electrical signal representative of the corresponding coordinates of the target in a frame linked to the camera (for example "VISIOMAT” remote sensing system, produced by the companies "ALLEN-BRADLEY” and "ROBOTRONICS").
  • the gripping means 25 may comprise a subset of conversion 25a, suitable for transforming, if necessary, the coordinates representative of the situation of the target in the coordinate system linked to the camera into operational coordinates in relation to a reference system linked to the base of the robot.
  • the storage means 26 comprise memories containing data representative of the possibilities of movement of the different components used: actuators and links thereof on the platforms.
  • the number of data to be stored is 4 per actuator (minimum length, maximum length, maximum swivel angle of its basic link, maximum swivel angle of its head link), or for the whole robot: 24 n (where n is the number of stages).
  • the actuators and connections of a stage will be identical to each other, which will reduce to 4 the number of parameters representative of the accessible space of this stage.
  • some stages may be identical and the number of data to be stored becomes equal to 4 n ′, where n ′ ⁇ n corresponds to the number of different types of stages. It is therefore understandable that such storage is very light in memory space required.
  • the storage means 26 comprise memories containing, for each floor architecture, relationships linking the accessible space data constituted in the example, by a quarter, by the positions x, y , z from the center of the platform with respect to the previous platform, on the other hand, in each position, by the possible rotation ⁇ around all the directions of space.
  • possible rotation ⁇ is meant for a given position, the smallest value among the set of maximum rotation angles around all directions.
  • FIG. 8a is a diagram giving the possible angle ⁇ as a function of x, y and z.
  • This family of curve obtained point by point by the calculation presents a discontinuity and can be modeled by two families of lines as shown diagrammatically in the diagram of figure 8b. These lines are represented by equations of the aforementioned type and are stored in the means 26 in the form of a calculation program capable of solving these equations. (We can see that for an optimum altitude z, the possible angles ⁇ go through a maximum).
  • the space data accessible by each platform are stored in the storage means 26 in the form of a database.
  • FIG. 9a symbolizes the space accessible, in position, through the center of a platform with respect to the previous platform.
  • Figures 9b, 9c and 9d are horizontal sections of this space at different heights, H1, H2, H3 respectively.
  • This accessible space is divided into a three-dimensional mesh and, for each node of the mesh, a table, itself three-dimensional, is stored, as shown schematically in FIG. 9b, relating to the possible rotations at this node.
  • the rotations are discretized by amplitudes (for example, degree by degree).
  • a given box corresponds to three discrete values of predetermined angles of rotation (r1, r2, r3) and contains information in binary of possibility or impossibility of satisfying the combination r1 , r2, r3 at node x, y, z.
  • the database is previously established by the calculation by establishing by a conventional mesh the nodes and the tables corresponding and by testing the possibility or the impossibility for each box of each table (taking into account the positions and orientations corresponding to said box), the database then being stored in the memories of the means 26.
  • the configuration calculation means 27 are intended to determine a robot configuration (by the set of generalized coordinates: coordinates of a coordinate system linked to each platform with respect to the previous platform or to the base) in which the terminal is in the final situation to be reached (position, orientation).
  • These configuration calculation means constituted by a processor of a type known per se include an iterative calculation program, the flow diagram of which is drawn in FIG. 10.
  • these calculation means acquire the final situation to be reached by the terminal Xd (operational coordinates entered: position, orientation) and an initial situation X of said terminal.
  • the latter can be represented by arbitrary coordinates previously stored in an auxiliary memory of the processor or by coordinates calculated during a prior step from signals from the sensors (then representing the real configuration of the robot at the instant considered) ; in the latter case, the processor is provided with an auxiliary calculation unit which is capable of providing the operational coordinates corresponding to a given configuration.
  • the first iterative calculation operation consists in calculating the mathematical distance d between the final situation and the initial situation previously acquired. This distance is determined by a calculation vector, term to term.
  • the Jacobian displacement matrix [J] is calculated corresponding to the initial configuration or to the configuration obtained in the previous step.
  • the Jacobian displacement matrix consists of terms each representing the first derivative of the operational coordinates with respect to each of the generalized coordinates of all the stages.
  • n is the number of operational coordinates representative of a final situation
  • j varying from 1 to m, where m is the total number of generalized coordinates representative of a configuration of the robot.
  • the multiplication with distance or a fraction thereof provides a set of increments [Jinv] (r. D ) which are then added to the generalized coordinates q representing the configuration of the robot in the previous step to obtain new generalized coordinates representing the new robot configuration.
  • the iterative procedure continues with a verification test of membership of the situations represented by the generalized coordinates obtained, with the accessible situations represented by the accessible space data stored in the storage means 26.
  • the new configuration is validated to go to the next calculation step.
  • the substitution criterion may consist in seeking an accessible situation, first by modifying -t-, then if necessary modifying Z, finally, if necessary, modifying ⁇ .
  • point P we first modify the value -t- to give it a value 0, then we modify the ordinate Z up to point P ′ where we reach an accessible situation (p, Zp ′ , O).
  • This substitution criterion favors rotations.
  • other criteria can be used depending on the application.
  • FIG. 11 illustrates a particular program for implementing the operations of verification and substitution op (highlighted in a discontinuous frame in FIG. 10).
  • This flowchart relates to the case where a database is stored in the storage means containing for each cylinder the lengths, minimum and maximum, and maximum angles of pivoting with respect to the norms at the two neighboring platforms.
  • a test on each length 1i thus calculated is carried out: if one of the lengths 1i is outside the range minimum length - maximum length (output: no), a substitution program is implemented which consists in varying homothetically all the lengths calculated in order to bring the overshoot values within the authorized range.
  • the new generalized coordinates for the stage considered are calculated (classic iterative calculation involving a square Jacobian matrix).
  • a test on each angle ⁇ i thus calculated is carried out: if one of the angles ⁇ i exceeds the maximum value (exit: no), a substitution program by successive approximations is implemented (dichotomy method); this program consists in reducing the lengths 1i in a given ratio compared to an average length, then in calculating the corresponding angles ⁇ i and in redoing the non-overshoot test, these operations being repeated until the angles calculated become at plus equal to the maximum allowable values.
  • FIG. 12 illustrates the configurations of the robot, in the iteration steps k-1 and k.
  • This determination is made by a geometric calculation consisting in calculating the operational coordinates of the terminal (relative to a reference frame linked to the base) from the generalized coordinates of all the floors (set of coordinates of each platform in a reference frame linked to each previous platform).
  • This conventional calculation in particular uses matrices for passing from a reference linked to one stage to another linked to the preceding stage to calculate step by step the absolute coordinates of the platforms from the base to the terminal.
  • the configuration calculation means 27 comprise a counter of iterative steps in order to stop the process when a determined number of iterations is reached without obtaining the result (that is to say d ⁇ e). In practice, this number will depend on the application and the precision -e- desired (of the order of 10 to 50). It is then estimated that the situation to be reached by the terminal is outside the domain accessible from the robot.
  • the generalized coordinates obtained at the end of the iterative calculation are delivered to the state calculation means 28, which transform them, for each actuator of the stage considered, into state information representative of the state that these actuators must take to arrange the stage considered in the calculated situation which corresponds to it.
  • the calculation of the states consists in a geometric calculation of the lengths between points of articulations of the actuators.
  • the state calculation means deliver for each stage six scalars representative of said lengths between points of articulations, towards the servo interface 30.
  • the latter which can be of the conventional "P.I.D.” type ("proportional, integral, derivative” command), is either digital or analog with conversion.
  • the robot physically takes the form of the calculated configuration.
  • the lengths of the actuators which correspond to specific final terminal situations, can be stored in the state storage means 29, in order to perform repetitive tasks without redoing the configuration calculations, the state information then being injected directly in the servo interface 30.
  • FIG. 13 presents an architectural variant of a robot, in which each platform 33 is formed by a crown (trellis or solid crown) provided with three projecting zones on the upper side and three projecting zones on the lower side. These areas are angularly offset by 60 °.
  • the upper protruding zones each carry the articulation of two actuators of the stage, while the lower protruding zones each carry the articulation of two actuators of the stage following.
  • FIG. 14 illustrates another embodiment of the robot, which differs from the previous ones by the elongated shape of the platforms, the other characteristics being identical.
  • Each platform 34 is constituted by an elongated rigid member: tubular cylinder or lattice.
  • the actuators of a stage are articulated on one end 34a of the platform of the stage in question, the actuators of the following stage being articulated on the opposite end 34b of said platform.
  • Such a robot is able to cover a very large area having regard to the number of stages, but at the cost of a more limited robot workspace in the immediate vicinity of the base.
  • FIG. 15 illustrates another variant in which auxiliary stages such as 35 are interposed between already described modular stages of the robot.
  • Each auxiliary stage has a geometry similar to that of the modular stages, but two, three or four actuators are replaced by rigid bars such as 36, so as to obtain an angular closed isostatic structure with six elements. In the example drawn, these six elements are formed by four actuators and two rigid bars.
  • the length of the rigid bars 36 is chosen in relation to that (minimum or maximum) of the actuators in order to shift the location of the working space of the robot towards such or such sector.
  • Such a robot is interesting in certain applications where very great redundancy would be superfluous, because it makes it possible to reduce the cost of the structure and that of the control (due to the reduced number of actuators), while retaining the triangulated geometry of the structure and the advantages inherent in it (great lightness vis-à-vis the admissible loads).

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Abstract

PCT No. PCT/FR88/00026 Sec. 371 Date Aug. 16, 1989 Sec. 102(e) Date Aug. 16, 1989 PCT Filed Jan. 19, 1988 PCT Pub. No. WO88/05712 PCT Pub. Date Aug. 11, 1988.The invention relates to a redundant robot of the modular type permitting displacement of a terminal from an initial position to a final position. This robot comprises a succession of stages (1i-1, 1i), each constituting a platform and six actuators arranged according to a closed angular architecture, a system of sensors associated with each stage, and control means permitting determining a configuration of the robot corresponding to the final position to be attained by the terminal and remotely operating the actuators for arranging the various stages according to this configuration. The control means comprises in particular means (26) for storing the space accessible by each platform, means (25) for inputting the final position to be attained, means (27) for computing the configuration of the robot, means (28) for computing the states of the actuators and a servo-interface for the latter.

Description

L'invention concerne un robot redondant de type modulaire, permettant de déplacer un terminal depuis une situation initiale vers une situation finale.The invention relates to a redundant robot of the modular type, making it possible to move a terminal from an initial situation to a final situation.

De nombreux robots ont été conçus pour automatiser des tâches dans un processus industriel ou autre, ou pour intervenir dans un environnement inaccessible à l'homme.Many robots have been designed to automate tasks in an industrial or other process, or to intervene in an environment inaccessible to humans.

Les robots les plus anciens, dits robots industriels, ont une architecture mécanique constituée de corps ou maillons liés entre eux de façon à permettre une rotation ou une translation d'un maillon par rapport aux maillons voisins. Les maillons sont généralement différents les uns des autres en vue de spécialiser le robot à un type de tâche donné. Le défaut essentiel de ces robots réside dans leur mécanique complexe et coûteuse, et dans leur masse très élevée rapportée à la charge utile pouvant être déplacée et ce, essentiellement en raison des conditions de travail à la flexion et torsion des éléments constitutifs de ces robots. De plus, ces robots ne sont pas redondants et sont donc inaptes à fonctionner correctement en cas de défaillance d'une ou plusieurs mobilités.The oldest robots, called industrial robots, have a mechanical architecture made up of bodies or links linked together so as to allow rotation or translation of a link relative to the neighboring links. The links are generally different from each other in order to specialize the robot for a given type of task. The essential defect of these robots lies in their complex and costly mechanics, and in their very high mass in relation to the payload that can be moved, this essentially due to the working conditions for bending and twisting of the constituent elements of these robots. In addition, these robots are not redundant and are therefore unable to function properly in the event of the failure of one or more mobilities.

Des robots, dits robots redondants, ont été conçus plus récemment pour intervenir dans des milieux encombrés ou quasi-fermés. Par "robot redondant", on entend un robot possédant des mobilités en nombre surabondant par rapport au nombre des mobilités nécessaires et suffisantes pour positionner et orienter un terminal dans l'espace. Leurs mobilités en nombre redondant permettent d'assurer un positionnement et une orientation du terminal de plusieurs manières différentes, de sorte que ces robots bénéficient d'une souplesse d'emploi beaucoup plus grande que les précédents.Robots, called redundant robots, have been designed more recently to intervene in congested or almost closed environments. By “redundant robot”, is meant a robot having a number of mobilities that is overabundant in relation to the number of mobilities necessary and sufficient to position and orient a terminal in space. Their redundant number of mobilities make it possible to ensure positioning and orientation of the terminal in several different ways, so that these robots benefit from a much greater flexibility of use than the previous ones.

Les brevets ou documents suivants illustrent des robots existants:

  • ― FR 2494618 décrivant un robot du type trompe d'éléphant à déformation dans un plan (défaut: espace accessible très limité),
  • ― WO 84/04722 décrivant un robot articulé dont les maillons sont commandés individuellement par des systèmes à câbles (défaut: effondrement partiel ou total du robot en cas de rupture d'un câble),
  • ― FR 2378612 décrivant un bras polyarticulé à déplacement spatial commandable par câbles depuis la base (défaut: espace accessible relativement limité),
  • ― EP 0017016 décrivant un bras flexible à déplacement spatial commandable par câbles (défaut: robot non commandable en cas de défaillance d'une transmission),
  • ― FR 2339470 décrivant un bras souple à maillons spatiaux permettant des rotations dans tous les sens (défaut: espace accessible relativement limité),
  • ― EP 0108549, EP 0085307 et EP 0077609 décrivant des bras à rotations multiples, aptes à se déplacer dans un espace encombré (défaut: charge supportée très limitée),
  • ― FR 2537909 décrivant un dispositif de liaison du type poignet, permettant des déplacements précis de puissance élevée (défaut: amplitudes faibles).
  • ― Soviet Engineering Research, vol. 2 n° 12 décembre 1982, pages 75-78, Melton Mowbrav, A.SH. KOLISTOR "Development and investigation of industrial robots based on specification by 1- coordinates", représentant l'état de la technique le plus proche visant un robot à 6 vérins par étages.
The following patents or documents illustrate existing robots:
  • - FR 2494618 describing a robot of the elephant trunk type with deformation in a plane (default: very limited accessible space),
  • - WO 84/04722 describing an articulated robot whose links are individually controlled by cable systems (default: partial or total collapse of the robot in the event of a cable break),
  • - FR 2378612 describing a polyarticulated arm with spatial displacement controllable by cables from the base (default: relatively limited accessible space),
  • - EP 0017016 describing a flexible arm with spatial displacement controllable by cables (default: robot not controllable in the event of a transmission failure),
  • - FR 2339470 describing a flexible arm with spatial links allowing rotations in all directions (default: relatively limited accessible space),
  • - EP 0108549, EP 0085307 and EP 0077609 describing arms with multiple rotations, able to move in a congested space (default: very limited supported load),
  • - FR 2537909 describing a wrist-type connection device, allowing precise movements of high power (default: low amplitudes).
  • - Soviet Engineering Research, vol. 2 No. 12 December 1982, pages 75-78, Melton Mowbrav, A.SH. KOLISTOR "Development and investigation of industrial robots based on specification by 1- coordinates", representing the closest state of the art targeting a robot with 6 cylinders per stage.

La structure mécanique décrite dans le dernier article ci-dessus visé semble posséder de remarquables potentialités, nais de difficiles problèmes de commande, non résolus jusqu'à ce jour, empêchent en fait que ces potentialités soient exploitées. En effet, si dans un système à étage unique, il existe une relation géométrique simple donnant la longueur des six vérins en fonction de la situation du terminal, ce n'est plus le cas dans un système où plusieurs étages sont combinés; il n'y a plus alors de relation simple permettant à partir d'une situation finale désirée, de déduire les longueurs des vérins et l'article sus-évoqué ne fournit aucun enseignement pour opérer la commande effective d'un tel robot.The mechanical structure described in the last article referred to above seems to have remarkable potentials, but difficult control problems, which have not been solved to date, actually prevent these potentials from being exploited. Indeed, if in a single-stage system, there is a simple geometric relationship giving the length of the six cylinders according to the situation of the terminal, this is no longer the case in a system where several stages are combined; there is then no longer a simple relation allowing, from a desired final situation, to deduce the lengths of the jacks and the above-mentioned article does not provide any instruction for operating the effective control of such a robot.

La présente invention se propose de fournir un robot perfectionné du type redondant ci-dessus évoqué, doté d'une commande permettant d'en exploiter toutes les potentialités.The present invention proposes to provide an advanced robot of the above-mentioned redundant type, provided with a control making it possible to exploit all its potentials.

Par "robot", on entend un système mécanique articulé constitué par un enchaînement d'au moins deux étages, auquel est associée une unité de commande. Dans la suite, on utilisera, d'une façon générale, le vocabulaire habituellement employé dans le domaine technique de la robotique.By "robot" is meant an articulated mechanical system constituted by a sequence of at least two stages, with which is associated a control unit. In the following, we will generally use the vocabulary usually used in the technical field of robotics.

Un autre objectif essentiel est de fournir un robot bénéficiant d'un grand nombre de mobilités, lui permettant d'intervenir dans des milieux encombrés grâce au choix d'un chemin adapté parmi un grand nombre de chemins possibles.Another essential objective is to provide a robot benefiting from a large number of mobilities, allowing it to intervene in congested environments thanks to the choice of a suitable path among a large number of possible paths.

Un objectif essentiel de l'invention est de permettre la manipulation de charges élevées, et de bénéficier d'un rapport charge/masse propre du robot, de valeur accrue par rapport aux robots connus.An essential objective of the invention is to allow the handling of high loads, and to benefit from a charge / mass ratio of the robot, of increased value compared to known robots.

Un autre objectif est de fournir un robot présentant une bonne tolérance aux pannes, c'est-à-dire apte à exécuter une tâche même en cas de panne de certains éléments.Another objective is to provide a robot with good fault tolerance, that is to say capable of performing a task even in the event of failure of certain elements.

Un autre objectif est de fournir un robot mécaniquement simple, dont les étages peuvent se répéter, soit à l'identique, soit à des modifications dimensionnelles près, chaque étage étant lui-même constitué d'éléments répétitifs.Another objective is to provide a mechanically simple robot, the stages of which can be repeated, either identically or with dimensional modifications, each stage itself being made up of repetitive elements.

Un autre objectif est de fournir un robot modulable, extensible à volonté suivant le type de tâche à accomplir.Another objective is to provide a modular robot, expandable at will according to the type of task to be accomplished.

Un autre objectif est de fournir un robot facile à dépanner en raison de la simplicité de sa structure et de la faible variété de composants constitutifs de celle-ci.Another objective is to provide an easy-to-troubleshoot robot due to the simplicity of its structure and the small variety of components that constitute it.

A cet effet, le robot visé par l'invention, permettant de déplacer un terminal depuis une situation initiale vers une situation finale, est du type modulaire comprenant au moins deux étages disposés les uns à la suite des autres, dont un premier étage solidaire d'une base et, à l'opposé, un dernier étage portant le terminal.To this end, the robot targeted by the invention, making it possible to move a terminal from an initial situation to a final situation, is of the modular type comprising at least two stages arranged one after the other, including a first stage integral with 'a base and, opposite, a top floor carrying the terminal.

Par "terminal", on entend tout système, actif ou passif, adapté à l'application envisagée, par exemple: pince, outil, caméra, etc...By "terminal" is meant any system, active or passive, suitable for the intended application, for example: pliers, tool, camera, etc ...

Par "situation", on entend une position et/ou une orientation dans l'espace, d'un repère lié à l'élément considéré par rapport à un repère de référence.By "situation" is meant a position and / or an orientation in space, of a reference linked to the element considered with respect to a reference reference.

Par "modulaire", on entend une répétition d'étages ayant le même type d'architecture, ces étages pouvant être rigoureusement identiques ou différer par leurs dimensions (des étages auxiliaires de type différent pouvant le cas échéant s'interposer entre les étages modulaires comme on le verra plus loin).By "modular" is meant a repetition of stages having the same type of architecture, these stages being able to be rigorously identical or differing by their dimensions (auxiliary stages of different type being able to intervene if necessary between the modular stages like we will see it later).

Le robot visé par l'invention est du type dans lequel chaque étage est composé d'une plate-forme et de six actionneurs linéaires, chacun articulé, vers une extrémité, sur la plate-forme de l'étage considéré par une liaison de type rotule, et vers son extrémité opposée, sur la plate-forme de l'étage précédent (ou sur la base pour le premier étage) par une liaison du même type, ces six actionneurs linéaires étant agencés selon une architecture angulée fermée de sorte que deux actionneurs voisins se trouvent articulés au voisinage l'un de l'autre sur une plate-forme et se trouvent, au contraire, articulés à distance sur l'autre plate-forme afin de former un angle entre eux, chaque étage comprenant un système de capteurs, adapté pour délivrer des signaux représentatifs de la situation relative de la plate-forme dudit étage par rapport à celle de l'étage précédent (ou par rapport à la base pour le premier étage).The robot targeted by the invention is of the type in which each stage is composed of a platform and six linear actuators, each articulated, towards one end, on the platform of the stage considered by a type connection ball joint, and towards its opposite end, on the platform of the preceding stage (or on the base for the first stage) by a connection of the same type, these six linear actuators being arranged according to a closed angulated architecture so that two neighboring actuators are articulated in the vicinity of one another on a platform and are, on the contrary, articulated at a distance on the other platform in order to form an angle between them, each stage comprising a system of sensors, adapted to deliver signals representative of the relative situation of the platform of said stage compared to that of the previous stage (or compared to the base for the first stage).

Ledit robot est caractérisé en ce qu'il comprend une unité de commande associée aux actionneurs et constituée par:

  • ― des moyens de stockage de données, dites données d'espace accessible, représentatives de situations accessibles par chaque plate-forme dans un système de référence lié à l'étage précédent (ou à la base pour le premier étage),
  • ― des moyens de saisie de coordonnées opérationnelles représentatives de la situation finale à atteindre,
  • ― des moyens de calcul, dits moyens de calcul de configuration, agencés pour accéder aux moyens de stockage des données d'espace accessible et pour recevoir les coordonnées opérationnelles issues des moyens de saisie, lesdits moyens de calcul de configuration contenant un programme de calculs itératifs selon la procédure suivante:
    • · calcul de la distance entre, d'une part, la situation du terminal correspondant à la configuration obtenue à l'étape précédente et, d'autre part, la situation finale désirée,
    • · calcul de la matrice Jacobienne de déplacement associée à la configuration obtenue à l'étage précédente,
    • · exécution d'opérations logiques entre la matrice Jacobienne et la distance en vue de déterminer une nouvelle situation par plate-forme, l'ensemble desdites situations étant représentatives d'une nouvelle configuration du robot,
    • · vérification de l'appartenance de ces situations avec les situations accessibles pour chaque plate-forme et, en cas de non-appartenance, substitution de la situation calculée par une situation accessible,
    • · détermination de la situation du terminal correspondant à la nouvelle configuration,
    • · itération de cette procédure jusqu'à obtenir une distance entre la situation finale et la dernière situation calculée du terminal, inférieure à un écart prédéterminé, en vue de déterminer une configuration du robot pour laquelle le terminal est situé dans la situation finale et de délivrer des coordonnées généralisées représentatives de ladite configuration ou une information d'impossibilité,
  • ― des moyens de calcul, dits moyens de calcul d'états, agencés pour recevoir les coordonnées généralisées représentatives de la configuration du robot et adaptés pour calculer, pour chaque étage, des informations d'état correspondant à ses six actionneurs linéaires,
  • ― une interface d'asservissement, agencée pour recevoir les informations d'état issues des moyens de calcul d'états ainsi que les signaux issus du système de capteurs et adaptée pour délivrer des grandeurs de commande propres à asservir chacun des actionneurs linéaires.
Said robot is characterized in that it comprises a control unit associated with the actuators and consisting of:
  • - data storage means, called accessible space data, representative of situations accessible by each platform in a reference system linked to the previous floor (or to the base for the first floor),
  • - means for entering operational coordinates representative of the final situation to be achieved,
  • - calculation means, called configuration calculation means, arranged to access the storage means accessible space data and to receive the operational coordinates from the input means, said configuration calculation means containing an iterative calculation program according to the following procedure:
    • · Calculation of the distance between, on the one hand, the situation of the terminal corresponding to the configuration obtained in the previous step and, on the other hand, the desired final situation,
    • · Calculation of the Jacobian displacement matrix associated with the configuration obtained on the previous stage,
    • · Execution of logical operations between the Jacobian matrix and the distance in order to determine a new situation by platform, all of these situations being representative of a new configuration of the robot,
    • · Verification of the belonging of these situations with the accessible situations for each platform and, in case of non-belonging, substitution of the calculated situation by an accessible situation,
    • · Determination of the terminal situation corresponding to the new configuration,
    • · Iteration of this procedure until a distance between the final situation and the last calculated situation of the terminal, less than a predetermined deviation, in order to determine a configuration of the robot for which the terminal is located in the final situation and to deliver generalized coordinates representative of said configuration or information of impossibility,
  • Calculation means, called state calculation means, arranged to receive the generalized coordinates representative of the configuration of the robot and adapted to calculate, for each stage, state information corresponding to its six linear actuators,
  • - A servo interface, arranged to receive the state information from the state calculation means as well as the signals from the sensor system and adapted to deliver control quantities suitable for slaving each of the linear actuators.

Par "actionneur linéaire", on entend tout dispositif électrique, hydraulique, pneumatique, etc... apte à engendrer à la commande une translation entre ses deux extrémités par lesquelles cet actionneur est articulé sur la plate-forme de l'étage considérée et sur celle de l'étage précédent. Les actionneurs peuvent notamment être constitués par des vérins, des systèmes à vis/écrous, mais aussi par des mécanismes plus complexes du type mécanisme à compas, à crémaillère.By "linear actuator" is meant any electrical, hydraulic, pneumatic device, etc. capable of generating, on command, a translation between its two ends by which this actuator is articulated on the platform of the stage in question and on that of the previous floor. The actuators can in particular be constituted by jacks, screw / nut systems, but also by more complex mechanisms of the compass mechanism, rack type.

Par "liaison de type rotule", on entend de façon générale toute liaison rotative apte à permettre au moins deux rotations d'axes perpendiculaires, et en particulier: rotule (permettant trois rotations d'axes concourants), cardan (permettant deux rotations d'axes concourants), liaison composée (permettant deux rotations d'axes non concourants).By "ball joint type" is generally meant any rotary joint capable of allowing at least two rotations of perpendicular axes, and in particular: ball joint (allowing three rotations of concurrent axes), cardan joint (allowing two rotations of concurrent axes), compound link (allowing two rotations of non-concurrent axes).

Les "coordonnées opérationnelles" et "coordonnées généralisées" représentent respectivement la situation du terminal par rapport à un repère de référence, et la situation des plates-formes en considérant comme référence, pour chaque plate-forme, la plate-forme voisine.The "operational coordinates" and "generalized coordinates" respectively represent the situation of the terminal with respect to a reference frame of reference, and the situation of the platforms by considering as reference, for each platform, the neighboring platform.

Par "configuration du robot", on entend l'ensemble des coordonnées généralisées de tous les étages du robot, reflétant la configuration générale du robot dans l'espace.By "robot configuration" is meant the set of generalized coordinates of all the stages of the robot, reflecting the general configuration of the robot in space.

Par "information d'état", on entend pour chaque actionneur une information de commande, représentative de l'état que doit prendra ledit actionneur.By "status information" is meant for each actuator control information, representative of the state that said actuator should take.

Par "distance", on entend la distance mathématique dans un espace à n dimensions, où n est le nombre de coordonnées opérationnelles nécessaires pour représenter une situation (dans le cas le plus général: trois coordonnées de position et trois coordonnées d'orientation).By "distance" is meant the mathematical distance in an n-dimensional space, where n is the number of operational coordinates necessary to represent a situation (in the most general case: three position coordinates and three orientation coordinates).

Le robot conforme à l'invention est ainsi constitué d'étages qui, de par leur architecture triangulée, travaillent tous en traction/compression, aussi bien au niveau des actionneurs linéaires qu'à celui des plates-formes. Les plates-formes peuvent elles-mêmes être constituées par des systèmes triangulés liant les zones d'articulation des actionneurs, de façon à supprimer radicalement toute contrainte de flexion/torsion. Il est également possible, selon l'application, de prévoir des plates-formes de structure différente (couronne,...): certaines contraintes de flexion/torsion peuvent alors localement se développer dans ces plates-formes, mais conservent des valeurs réduites par rapport à celles s'exerçant dans la plupart des robots connus. Le robot peut ainsi posséder une structure légère, à faible déformation sous charge, capable de manipuler des masses élevées. La mise en série d'au moins deux étages de structure telle que ci-dessus définie entraîne une redondance de mobilités permettant d'obtenir une situation finale donnée du terminal par une multitude de combinaisons d'états des actionneurs. De plus, du fait de cette redondance, en cas de panne d'un ou de plusieurs actionneurs, l'espace accessible par le terminal (espace de travail du robot) se trouve réduit mais, pour un robot constitué d'au moins quelques étages, le nombre de mobilités demeure satisfaisant. L'unité de commande permet d'exploiter ces mobilités: à partir d'une situation initiale donnée, elle permet de déterminer ― si cela est possible ― une configuration correspondant à la situation finale à atteindre et de calculer les informations d'états correspondantes des actionneurs. La détermination de la configuration est effectuée à partir des coordonnées opérationnelles saisies (situation finale à atteindre) et des données d'espace accessible stockées dans les moyens de stockage sus-évoqués (ces données représentant l'espace accessible par chaque plate-forme dans un système de référence lié à la plate-forme de l'étage précédent). La procédure itérative définie procède par étape en utilisant pour l'étape en cours la configuration obtenue à l'étape précédente. Pour la première itération, on utilise une configuration initiale qui peut être soit entièrement conventionnelle, soit la configuration initiale réelle du robot calculée à partir des signaux issus des capteurs.The robot according to the invention thus consists of stages which, by their triangulated architecture, all work in traction / compression, both at the level of the linear actuators and at that of the platforms. The platforms can themselves be constituted by triangulated systems linking the articulation zones of the actuators, so as to radically remove any bending / torsional stress. It is also possible, depending on the application, to provide platforms of different structure (crown, etc.): certain bending / torsion stresses can then locally develop in these platforms, but keep values reduced by compared to those practiced in most known robots. The robot can thus have a light structure, with low deformation under load, capable of handling high masses. The placing in series of at least two stages of structure as defined above leads to a redundancy of mobilities making it possible to obtain a given final situation of the terminal by a multitude of combinations of states of the actuators. In addition, due to this redundancy, in the event of failure of one or more actuators, the space accessible by the terminal (robot workspace) is reduced but, for a robot made up of at least a few floors , the number of mobilities remains satisfactory. The control unit makes it possible to exploit these mobilities: from a given initial situation, it makes it possible to determine - if this is possible - a configuration corresponding to the final situation to be reached and to calculate the information of corresponding states of the actuators. The configuration is determined from the operational coordinates entered (final situation to be reached) and accessible space data stored in the above-mentioned storage means (these data representing the space accessible by each platform in a reference system linked to the platform of the previous floor). The defined iterative procedure proceeds step by step using for the current step the configuration obtained in the previous step. For the first iteration, an initial configuration is used which can either be entirely conventional, or the actual initial configuration of the robot calculated from the signals from the sensors.

L'utilisation de l'outil mathématique constitué par la matrice Jacobienne de déplacement associée à la configuration du robot permet une linéarisation simple de la relation liant les coordonnées opérationnelles et l'ensemble des coordonnées généralisées représentatives de cette configuration. Cette relation est facile à utiliser pour déterminer, par ses coordonnées généralisées, une nouvelle configuration du robot à partir de la configuration précédente connue, par des opérations logiques telles que inversion de la matrice Jacobienne et multiplication par la distance (ou une fraction de celle-ci). Malgré le caractère simplicatif de la relation Jacobienne, la procédure itérative par pas successifs permet une convergence jusqu'à l'obtention d'une précision inférieure à un écart prédéterminé.The use of the mathematical tool constituted by the Jacobian displacement matrix associated with the configuration of the robot allows a simple linearization of the relation linking the operational coordinates and the set of generalized coordinates representative of this configuration. This relation is easy to use to determine, by its generalized coordinates, a new configuration of the robot from the previous known configuration, by logical operations such as inversion of the Jacobian matrix and multiplication by the distance (or a fraction of this- this). Despite the simplicity of the Jacobian relation, the iterative procedure in successive steps allows convergence until obtaining a precision lower than a predetermined deviation.

Les vérifications d'appartenance effectuées dans le processus itératif sus-défini consistent à tester si les situations de la nouvelle configuration sont ou non accessibles, c'est-à-dire si la situation calculée de chaque plate-forme est une situation accessible de celle-ci. Dans la négative, la substitution consiste à remplacer la situation calculée non valide par une situation accessible suivant un critère préétabli, notamment de proximité.The membership checks carried out in the above-defined iterative process consist in testing whether the situations of the new configuration are accessible or not, that is to say if the calculated situation of each platform is an accessible situation of that -this. If not, the substitution consists of replacing the calculated situation that is not valid with an accessible situation according to a pre-established criterion, in particular proximity.

La détermination de la situation du terminal correspondant à la nouvelle configuration (le cas échéant avec substitution) s'effectue par un simple calcul géométrique à partir de l'ensemble des situations calculées représentatives de la configuration. Cette détermination permet de calculer la distance pour l'étape d'itération suivante.The determination of the terminal situation corresponding to the new configuration (if necessary with substitution) is carried out by a simple geometric calculation from all the calculated situations representative of the configuration. This determination calculates the distance for the next iteration step.

Selon un premier mode de réalisation, les moyens de stockage des données d'espace accessible comprennent des moyens de mémorisation, stockant pour chaque architecture d'étages une base de données contenant, pour chaque actionneur de l'étage considéré, les longueurs minimale et maximale de cet actionneur et les angles maximum que peut prendre ledit actionneur par rapport aux normales aux deux plate-formes auxquelles aboutit ledit actionneur.According to a first embodiment, the means for storing the data of accessible space comprises means of memorization, storing for each architecture of stages a database containing, for each actuator of the stage considered, the minimum and maximum lengths of this actuator and the maximum angles that said actuator can take relative to normal to the two platforms to which said actuator ends.

Ce mode de réalisation présente l'avantage, d'une part, de refléter de façon précise les possibilités de mouvements d'un étage (conditionnées par ses composants technologiques), d'autre part, de requérir peu d'espace mémoire, puisque quatre données par actionneur sont suffisantes pour caractériser l'espace accessible. Toutefois, comme on le verra plus loin, les calculs effectués par les moyens de calcul de configuration sont plus longs par rapport aux solutions suivantes.This embodiment has the advantage, on the one hand, of accurately reflecting the possibilities of movement of a stage (conditioned by its technological components), on the other hand, of requiring little memory space, since four enough data per actuator to characterize the accessible space. However, as will be seen below, the calculations made by the configuration calculation means are longer compared to the following solutions.

Selon un autre mode de réalisation, les moyens de stockage des données d'espace accessible comprennent des moyens de mémorisation d'un programme de calcul contenant, pour chaque architecture d'étage, des relations liant la position (x, y, z) du centre de la plate-forme de l'étage par rapport à la plate-forme voisine et la rotation possible (α) de ladite plate-forme suivant toutes les directions de l'espace.According to another embodiment, the means for storing the accessible space data comprise means for storing a calculation program containing, for each floor architecture, relations linking the position (x, y, z) of the center of the platform of the floor relative to the neighboring platform and the possible rotation (α) of said platform in all directions of space.

Dans cette réalisation, l'espace accessible par chaque plate-forme (dans un système de référence lié à la plate-forme précédente) est modélisé par des relations mathématiques liant les données d'espace accessible. Ces relations sont contenues dans le programme de calcul sus-évoqué qui est préalablement chargé dans les moyens de mémorisation, en fonction de l'architecture du robot. Il est à noter que par "programme", on entend aussi bien une série d'instructions constituant un logiciel, que des circuits câblés aptes à exécuter des instructions définies par ces circuits. Cette réalisation plus légère en temps de calcul a le défaut de conduire à une perte de possibilités de mouvements en raison de la modélisation.In this embodiment, the space accessible by each platform (in a reference system linked to the previous platform) is modeled by mathematical relationships linking the data of accessible space. These relationships are contained in the abovementioned calculation program which is previously loaded into the storage means, depending on the architecture of the robot. It should be noted that by "program" is meant both a series of instructions constituting software, and wired circuits capable of executing instructions defined by these circuits. This lighter realization in computation time has the defect of leading to a loss of possibilities of movements due to modeling.

Dans un autre mode de réalisation, les moyens de stockage des données d'espace accessible comprennent des moyens de mémorisation, stockant, pour chaque architecture d'étages, une base de données découpée en zones correspondant à des noeuds d'un maillage spatial: chaque zone contient des données représentatives, d'une part, de la position du noeud correspondant, d'autre part, des rotations possibles en ce noeud autour de directions prédéterminées.In another embodiment, the means for storing the data of accessible space comprise means of memorization, storing, for each architecture of stages, a database divided into zones corresponding to nodes of a spatial mesh: each zone contains data representative, on the one hand, of the position of the corresponding node, on the other hand, possible rotations in this node around predetermined directions.

Dans cette réalisation, l'espace accessible par chaque plate-forme (dans un système de référence lié à la plate-forme précédente) est découpé selon un maillage spatial et les situations des noeuds de ce maillage sont préalablement mémorisées dans les moyens de mémorisation, en fonction de l'architecture du robot. Les temps de calcul deviennent alors très courts, mais l'espace mémoire nécessaire est beaucoup plus important que dans les cas précédents.In this embodiment, the space accessible by each platform (in a reference system linked to the previous platform) is cut out according to a spatial mesh and the situations of the nodes of this mesh are stored beforehand in the storage means, depending on the architecture of the robot. The calculation times then become very short, but the memory space required is much larger than in the previous cases.

Par ailleurs, les moyens de saisie des coordonnées opérationnelles représentatives de la situation finale à atteindre peuvent comprendre une interface homme/machine, adaptée pour permettre de saisir des coordonnées représentatives de la position spatiale finale à atteindre par l'origine d'un repère donné lié au terminal et/ou des coordonnées représentatives de l'orientation finale à atteindre par ledit repère. Dans ce cas, ces moyens de saisie peuvent revêtir la forme d'un clavier de saisie, d'un écran tactile, d'un écran associé à un stylo de pointage électronique, d'un système de manipulation associé à un écran, d'un système de reconnaissance vocale, etc...Furthermore, the means for inputting the operational coordinates representative of the final situation to be achieved may comprise a man / machine interface, adapted to enable the input of coordinates representative of the final spatial position to be reached by the origin of a given linked reference point. to the terminal and / or coordinates representative of the final orientation to be reached by said reference. In this case, these input means can take the form of an input keyboard, a touch screen, a screen associated with an electronic pointing pen, a manipulation system associated with a screen, a voice recognition system, etc ...

Ces moyens de saisie peuvent également comprendre une interface vers un moyen d'injection de coordonnées opérationnelles, stockées ou calculées par ailleurs, en vue de la réalisation de tâche en l'absence d'opérateur.These input means can also include an interface to a means for injecting operational coordinates, stored or calculated elsewhere, with a view to carrying out a task in the absence of an operator.

Ces moyens de saisie peuvent également comprendre, d'une part, un système de télédétection adapté pour détecter une cible à atteindre, d'autre part, des moyens de calcul adaptés pour délivrer à partir des signaux issus du système de télédétection, les coordonnées représentatives de la position spatiale et/ou de l'orientation spatiale de la cible. Le système de télédétection, classique en lui-même (caméra notamment vidéo, système de capteurs magnétiques, ultrasonores ou infrarouges...) peut être embarqué sur le robot ou indépendant de celui-ci.These input means can also include, on the one hand, a remote sensing system adapted to detect a target to be reached, on the other hand, calculation means adapted to deliver from the signals from the remote sensing system, the representative coordinates the spatial position and / or the spatial orientation of the target. The remote sensing system, conventional in itself (notably a video camera, magnetic, ultrasonic or infrared sensor system, etc.) can be embedded on the robot or independent of it.

La structure de chaque étage du robot conforme à l'invention peut être constituée selon le mode de réalisation suivant: les six actionneurs de chaque étage sont articulés, d'une part, sur la plate-forme de l'étage considéré en trois zones distinctes de ladite plate-forme, d'autre part, sur la plate-forme de l'étage précédent (ou sur la base pour le premier étage) en trois zones distinctes de ladite plate-forme (ou de ladite base); de plus, ces six actionneurs peuvent être identiques, les trois zones d'articulation des actionneurs sur la plate-forme de l'étage considéré et les trois zones d'articulation desdits actionneurs sur la plate-forme de l'étage précédent étant agencées aux sommets de triangles équilatéraux.The structure of each stage of the robot according to the invention can be constituted according to the following embodiment: the six actuators of each stage are articulated, on the one hand, on the platform of the stage considered in three distinct zones of said platform, d 'on the other hand, on the platform of the previous floor (or on the base for the first floor) in three distinct zones of said platform (or said base); in addition, these six actuators can be identical, the three articulation zones of the actuators on the platform of the stage in question and the three articulation zones of said actuators on the platform of the preceding stage being arranged at vertices of equilateral triangles.

En outre, les plates-formes peuvent avoir des formes diverses, fonctions de l'application. Généralement, elles seront réalisées par une structure triangulée creuse, préservant un passage central le long du robot en vue de loger un faisceau de transmission (alimentation et commande des actionneurs, transmission des signaux issus des capteurs, éventuellement, alimentation et commande d'un terminal actif).In addition, the platforms can have various forms, depending on the application. Generally, they will be produced by a hollow triangulated structure, preserving a central passage along the robot in order to accommodate a transmission beam (supply and control of the actuators, transmission of signals from the sensors, possibly, supply and control of a terminal active).

Le cas échéant, une ou plusieurs plates-formes peuvent être constituées par une membrure rigide de forme allongée, les actionneurs de l'étage concerné étant articulés sur une extrémité de ladite membrure, et les actionneurs de l'étage suivant étant articulés sur l'extrémité opposée de ladite membrure. On obtient ainsi un robot plus filiforme, de portée accrue pour un nombre d'étage donné.Where appropriate, one or more platforms may be constituted by a rigid member of elongated shape, the actuators of the stage concerned being articulated on one end of said member, and the actuators of the following stage being articulated on the opposite end of said member. A more threadlike robot is thus obtained, with an increased range for a given number of stages.

De plus, il est possible de prévoir des étages auxiliaires interposés entre les étages précités dits étages modulaires, chaque étage auxiliaire étant composé d'une plate-forme, de deux, trois ou quatre actionneurs linéaires et d'un nombre complémentaire de barres rigides, de façon à obtenir une structure isostatique angulée fermée à six côtés, présentant une géométrie analogue à celle d'un étage modulaire. Ces dispositions permettent, dans certaines applications, de simplifier le robot lorsque toutes les mobilités ne sont pas nécessaires.In addition, it is possible to provide auxiliary stages interposed between the aforementioned stages known as modular stages, each auxiliary stage being composed of a platform, two, three or four linear actuators and a complementary number of rigid bars, so as to obtain an angular isostatic structure closed with six sides, having a geometry similar to that of a modular stage. These provisions make it possible, in certain applications, to simplify the robot when all the mobilities are not necessary.

L'invention ayant été exposée dans sa forme générale, d'autres caractéristiques, buts et avantages ressortiront de la description qui suit en référence aux dessins annexés qui en présentent, à titre d'exemples non limitatifs, des modes de réalisation; sur ces dessins:

  • ― la figure 1 est une vue schématique en perspective, avec arrachés partiels, d'un mode de réalisation de robot,
  • ― la figure 2 est une coupe par un plan vertical AA′ d'un étage du robot,
  • ― la figure 3 est une vue de dessus d'une plate-forme avec le départ des actionneurs,
  • ― la figure 4 est une vue schématique éclatée d'un actionneur linéaire,
  • ― la figure 5 est une vue en perspective d'un détail, montrant une zone d'articulation d'une plate-forme,
  • ― la figure 6 est une coupe de détail, par un plan vertical, d'une variante de robot,
  • ― la figure 7 est un schéma bloc illustrant l'unité de commande du robot,
  • ― les figures 8a et 8b sont des diagrammes illustrant un premier mode de détermination des situations accessibles pour une plate-forme,
  • ― les figures 9a, 9b, 9c et 9d sont des schémas illustrant un autre mode de détermination de ces situations accessibles,
  • ― les figures 10 et 11 sont des logigrammes illustrant la procédure itérative de détermination d'une configuration du robot par les moyens de calcul de configuration,
  • ― la figure 12 est une vue schématique illustrant, en coupe, l'espace accessible en position par le robot et le processus itératif de détermination de la configuration correspondant à une situation à atteindre,
  • ― les figures 13, 14 et 15 sont des vues schématiques de variantes de robot (zones d'articulation décalées, plate-forme de forme allongée, présence d'étages auxiliaires).
The invention having been explained in its general form, other characteristics, objects and advantages will emerge from the description which follows with reference to annexed drawings which show, by way of nonlimiting examples, embodiments; on these drawings:
  • FIG. 1 is a schematic perspective view, partially broken away, of an embodiment of a robot,
  • FIG. 2 is a section through a vertical plane AA ′ of a stage of the robot,
  • FIG. 3 is a top view of a platform with the departure of the actuators,
  • FIG. 4 is an exploded schematic view of a linear actuator,
  • FIG. 5 is a perspective view of a detail, showing an area of articulation of a platform,
  • FIG. 6 is a detail section, through a vertical plane, of a variant of the robot,
  • FIG. 7 is a block diagram illustrating the robot control unit,
  • FIGS. 8a and 8b are diagrams illustrating a first mode of determining the accessible situations for a platform,
  • FIGS. 9a, 9b, 9c and 9d are diagrams illustrating another method of determining these accessible situations,
  • FIGS. 10 and 11 are flow diagrams illustrating the iterative procedure for determining a configuration of the robot by the configuration calculation means,
  • FIG. 12 is a schematic view illustrating, in section, the space accessible in position by the robot and the iterative process of determining the configuration corresponding to a situation to be achieved,
  • - Figures 13, 14 and 15 are schematic views of robot variants (offset articulation zones, elongated platform, presence of auxiliary stages).

Le robot représenté à titre d'exemple comprend une architecture modulaire telle que schématisée aux figures 1 à 5, associée à une unité de commande dont le schéma bloc est fourni à la figure 7.The robot represented by way of example comprises a modular architecture as shown diagrammatically in FIGS. 1 to 5, associated with a control unit whose block diagram is provided in FIG. 7.

Ce robot comprend plusieurs étages superposés tel que premier étage 1p, étages courants 1i₋₁, 1i, et dernier étage 1d.This robot comprises several superimposed stages such as first stage 1p, current stages 1 i ₋₁, 1 i , and last stage 1d.

Chaque étage est essentiellement formé par une plate-forme 2, par six actionneurs linéaires identiques tels que 3a, 3b, 3c, 3d, 3e et 3f pour l'étage courant et par un jeu de capteurs tels que schématisés en 4a, 4b, 4c à la figure 2 (dans un souci de simplification, ces capteurs n'ont pas été représentés à la figure 1).Each stage is essentially formed by a platform 2, by six identical linear actuators such as 3a, 3b, 3c, 3d, 3e and 3f for the current stage and by a set of sensors as shown schematically in 4a, 4b, 4c in FIG. 2 (for the sake of simplification, these sensors have not been shown in FIG. 1).

Les vérins du premier étage 1p sont attelés sur une base 5 qui peut être formée par une plate-forme 5a fixée sur un socle 5b.The cylinders of the first stage 1p are coupled to a base 5 which can be formed by a platform 5a fixed on a base 5b.

La plate-forme 6 du dernier étage 1d porte un terminal 7 adapté à la tâche à accomplir (pince dans l'exemple représenté, éventuellement associée à une caméra de télédétection).The platform 6 of the last stage 1d carries a terminal 7 adapted to the task to be performed (clamp in the example shown, possibly associated with a remote sensing camera).

Le nombre d'étages est au moins égal à 2 et sera en pratique de l'ordre de 4 à 12, ce nombre modifiable étant adapté à la tâche à accomplir.The number of stages is at least equal to 2 and will in practice be of the order of 4 to 12, this modifiable number being adapted to the task to be accomplished.

En l'exemple représenté, chaque plate-forme telle que 2 est constituée par trois blocs d'articulations 8a, 8b, 8c disposés aux sommets d'un triangle équilatéral et reliés par des entretoises 9a, 9b, 9c agencées en triangle.In the example shown, each platform such as 2 consists of three blocks of articulations 8a, 8b, 8c arranged at the vertices of an equilateral triangle and connected by spacers 9a, 9b, 9c arranged in a triangle.

Chaque bloc d'articulation est formé par un tronçon de poutre coudée 10 à section en forme de H portant au-dessus et au-dessous de sa semelle des axes d'articulations tels que 11 reliés aux joues de la poutre. Chaque axe 11 est pourvu d'une partie sphérique 12 guidant une autre partie sphérique 13 solidaire de l'extrémité de la tige de l'actionneur considéré, l'ensemble 11, 12, 13 formant une rotule qui autorise une rotation, d'une part, autour de l'axe 11, d'autre part, autour de l'axe longitudinal de la tige d'actionneur, enfin autour d'un troisième axe, orthogonal aux deux autres.Each articulation block is formed by a bent section of beam 10 with an H-shaped section carrying above and below its sole articulation axes such as 11 connected to the cheeks of the beam. Each axis 11 is provided with a spherical part 12 guiding another spherical part 13 integral with the end of the rod of the actuator considered, the assembly 11, 12, 13 forming a ball joint which allows rotation, of a part, around the axis 11, on the other hand, around the longitudinal axis of the actuator rod, finally around a third axis, orthogonal to the other two.

Dans l'exemple décrit, sur chaque plate-forme, les trois zones d'articulation des actionneurs de l'étage (au-dessous de la semelle) sont superposées avec les trois zones d'articulation des actionneurs de l'étage suivant (au-dessus de la semelle), ce qui permet de prévoir uniquement trois blocs d'articulation par plate-forme.In the example described, on each platform, the three articulation zones of the actuators of the stage (below the sole) are superimposed with the three articulation zones of the actuators of the following stage (at above the sole), which allows only three articulation blocks per platform.

Les entretoises 9a, 9b, 9c sont soudées entre les blocs d'articulation 8a, 8b, 8c et en l'exemple, formées par des poutres à section rectangulaire.The spacers 9a, 9b, 9c are welded between the articulation blocks 8a, 8b, 8c and in the example, formed by beams with rectangular section.

On conçoit la simplicité structurelle d'une telle plate-forme qui, soumise uniquement à des contraintes en traction/compression, présente un excellent rapport charge admissible/masse.We can understand the structural simplicity of such a platform which, subjected only to tensile / compression stresses, has an excellent admissible load / mass ratio.

Les six actionneurs de chaque étage sont en l'exemple constitués par des actionneurs linéaires électriques de type connu en soi, tel que représenté à la figure 4. Chaque actionneur comprend un moteur électrique 14 porté par un carter 15 logeant un réducteur 16 qui entraîne en rotation une vis 17 logée dans une extension cylindrique du carter 15.The six actuators of each stage are in the example constituted by electric linear actuators of a type known per se, as shown in FIG. 4. Each actuator comprises an electric motor 14 carried by a casing 15 housing a reducer 16 which drives in rotation of a screw 17 housed in a cylindrical extension of the casing 15.

Le carter 15 est articulé sur une plate-forme par l'entremise d'une rotule telle que déjà décrite.The casing 15 is articulated on a platform by means of a ball joint as already described.

En outre, chaque actionneur comprend un écrou 18 en prise avec la vis 17 et solidaire d'un fourreau 19. Ce fourreau est claveté avec l'extension du carter afin de pouvoir coulisser par rapport à celle-ci sans rotation relative. L'extrémité du fourreau 19 est articulée par l'entremise d'une rotule telle que décrite sur la plate-forme voisine.In addition, each actuator comprises a nut 18 engaged with the screw 17 and integral with a sheath 19. This sheath is keyed with the extension of the casing so that it can slide relative to the latter without relative rotation. The end of the sheath 19 is articulated by means of a ball joint as described on the neighboring platform.

Bien entendu, d'autres types d'actionneurs peuvent être prévus (vérins hydrauliques, pneumatiques...).Of course, other types of actuators can be provided (hydraulic cylinders, pneumatic ...).

Les six actionneurs d'un étage sont agencés comme le montrent les figures, selon une architecture angulée fermée, de sorte que deux actionneurs voisins soient articulés, pour une plate-forme, sur le même bloc d'articulation et, pour la plate-forme voisine, sur deux blocs voisins.The six actuators of a stage are arranged as shown in the figures, according to a closed angulated architecture, so that two neighboring actuators are articulated, for a platform, on the same articulation block and, for the platform neighbor, on two neighboring blocks.

En l'exemple représenté aux figures 1 et 2, les actionneurs voisins sont positionnés tête-bêche.In the example shown in Figures 1 and 2, the neighboring actuators are positioned head to tail.

La rotation parasite de chaque actionneur autour de son axe longitudinal est neutralisée, en l'exemple, par des ressorts tels que 20 qui relient les moteurs 14 entre eux (tout autre système pouvant être prévu).The parasitic rotation of each actuator about its longitudinal axis is neutralized, in the example, by springs such as 20 which connect the motors 14 to each other (any other system that may be provided).

Chaque actionneur électrique est associé à un capteur tel que 4a, 4b, 4c, apte à délivrer un signal représentatif de la longueur dudit actionneur. Par exemple, ces capteurs sont des capteurs linéaires à piste résistive, ayant un corps cylindrique solidaire de l'extension du carter 15 de l'actionneur et une tige mobile, fixée par son extrémité sur une patte solidaire du fourreau 19 dudit actionneur.Each electric actuator is associated with a sensor such as 4a, 4b, 4c, capable of delivering a signal representative of the length of said actuator. For example, these sensors are linear sensors with a resistive track, having a cylindrical body integral with the extension of the casing 15 of the actuator and a movable rod, fixed at its end on a lug integral with the sheath 19 of said actuator.

Les liaisons électriques vers les capteurs et les moteurs ainsi que vers le terminal si celui-ci est actif, sont guidées par une gaine symbolisée en 21 aux figures 1 et 2, passant dans les évidements centraux des plates-formes et courant le long du robot. Dans le cas d'un terminal hydraulique ou pneumatique, cette gaine contient également les conduits de fluide appropriés.The electrical connections to the sensors and motors as well as to the terminal if the latter is active, are guided by a sheath symbolized at 21 in FIGS. 1 and 2, passing through the central recesses of the platforms and running along the robot. . In the case of a hydraulic or pneumatic terminal, this sheath also contains the appropriate fluid conduits.

Le robot peut par ailleurs être extérieurement habillé d'une protection souple reliée aux plates-formes (par exemple soufflets fixés autour des plates-formes).The robot can also be dressed externally with a flexible protection connected to the platforms (for example bellows fixed around the platforms).

La figure 6 est une vue partielle d'une variante d'étage, dans laquelle les rotules précédentes sont remplacées par des cardans 22. Chaque cardan permet une rotation autour de deux axes perpendiculaires. Dans ce cas, le fourreau 19′ de l'actionneur n'est plus claveté sur l'extension du carter 15′ afin de permettre la rotation de ces deux éléments.FIG. 6 is a partial view of a variant stage, in which the preceding ball joints are replaced by universal joints 22. Each universal joint allows rotation around two perpendicular axes. In this case, the sheath 19 ′ of the actuator is no longer keyed to the extension of the casing 15 ′ in order to allow the rotation of these two elements.

De plus, la tige mobile de chaque capteur 4′ est solidaire d'une patte qui peut tourner autour du fourreau 19′.In addition, the movable rod of each sensor 4 ′ is integral with a lug which can rotate around the sheath 19 ′.

En outre, dans l'exemple représenté, les actionneurs d'un étage sont tous positionnés dans le même sens, avec leur moteur en partie basse, afin d'abaisser le centre de gravité de l'ensemble du robot.In addition, in the example shown, the actuators of a stage are all positioned in the same direction, with their motor in the lower part, in order to lower the center of gravity of the entire robot.

De plus, dans cet exemple, chaque plate-forme est constituée de deux plateaux identiques 37, 38 assemblés l'un sur l'autre par vis et écrous, avec des pions de centrage en vue de leur positionnement relatif. Les plateaux représentés à la figure ont une forme circulaire.In addition, in this example, each platform consists of two identical plates 37, 38 assembled one on the other by screws and nuts, with centering pins for their relative positioning. The trays shown in the figure have a circular shape.

Ce mode de réalisation permet des modifications de robot plus aisées. En effet, cette disposition fait apparaître des modules constitués par un plateau inférieur, le système de vérins et capteurs et un plateau supérieur, très faciles à ajouter ou supprimer sans modification des fixations des actionneurs.This embodiment allows easier robot modifications. Indeed, this arrangement shows modules constituted by a lower plate, the actuator and sensor system and an upper plate, very easy to add or remove without modifying the actuator fixings.

La figure 7 est un schéma bloc montrant l'unité de commande du robot, avec les liaisons symbolisées vers les divers étages du robot. Dans cet exemple, le terminal porte une pince et une caméra D.T.C. (dispositif à transfert de charge) symbolisée en 24.Figure 7 is a block diagram showing the robot control unit, with the symbolized links to the various stages of the robot. In this example, the terminal carries a clamp and a D.T.C. (charge transfer device) symbolized at 24.

L'unité de commande peut être logée dans une armoire qui est schématisée en 23 à la figure 1 près du socle 5.The control unit can be housed in a cabinet which is shown diagrammatically at 23 in FIG. 1 near the base 5.

Cette unité de commande comprend essentiellement les ensembles électroniques suivants: moyens de saisie 25 de coordonnées opérationnelles représentatives de la situation finale du terminal à atteindre, moyens de stockage 26 des données d'espace accessible par chaque plate-forme, moyens de calcul de configuration 27, moyens de calcul d'états 28, moyens auxiliaires de mémorisation d'états 29, interface d'asservissement 30.This control unit essentially comprises the following electronic assemblies: means for entering 25 operational coordinates representative of the final situation of the terminal to be reached, means for storing 26 data of space accessible by each platform, means for calculating configuration 27 , state calculation means 28, auxiliary state storage means 29, servo interface 30.

Les moyens de saisie 25 sont équipés d'une interface homme/machine 31 qui permet une entrée directe des coordonnées opérationnelles de la situation finale à atteindre: coordonnées de position du centre du terminal et coordonnées d'orientation, dans un trièdre de référence.The input means 25 are equipped with a man / machine interface 31 which allows direct entry of the operational coordinates of the final situation to be reached: position coordinates of the center of the terminal and orientation coordinates, in a reference trihedron.

La saisie peut également fonctionner en mode télédétection grâce à la caméra 24 qui délivre un flot d'informations séquencées vers une unité intermédiaire de traitement 32 adaptée pour élaborer et délivrer les coordonnées opérationnelles sus-évoquées représentatives de la situation finale à atteindre pour le terminal. La caméra 24 et l'unité de traitement 32 sont formées par tout système de télédétection de type connu en soi, apte à reconnaître une cible à atteindre (pièce mécanique...), à en extraire une information de position et/ou d'orientation et à délivrer un signal électrique représentatif des coordonnées correspondantes de la cible dans un repère lié à la caméra (par exemple système de télédétection "VISIOMAT", réalisé par les Sociétés "ALLEN-BRADLEY" et "ROBOTRONICS"). De plus, les moyens de saisie 25 peuvent comprendre un sous-ensemble de conversion 25a, adapté pour transformer, en cas de besoin, les coordonnées représentatives de la situation de la cible dans le repère lié à la caméra en coordonnées opérationnelles par rapport à un système de référence lié à la base du robot.The input can also operate in remote sensing mode thanks to the camera 24 which delivers a flow of sequenced information to an intermediate processing unit 32 adapted to develop and deliver the operational coordinates mentioned above representative of the final situation to be reached for the terminal. The camera 24 and the processing unit 32 are formed by any remote sensing system of the type known per se, capable of recognizing a target to be reached (mechanical part, etc.), of extracting position and / or position information therefrom. orientation and to deliver an electrical signal representative of the corresponding coordinates of the target in a frame linked to the camera (for example "VISIOMAT" remote sensing system, produced by the companies "ALLEN-BRADLEY" and "ROBOTRONICS"). In addition, the gripping means 25 may comprise a subset of conversion 25a, suitable for transforming, if necessary, the coordinates representative of the situation of the target in the coordinate system linked to the camera into operational coordinates in relation to a reference system linked to the base of the robot.

Par ailleurs, selon un premier mode de réalisation, les moyens de stockage 26 comprennent des mémoires contenant des données représentatives des possibilités de déplacement des différents composants utilisés: actionneurs et liaisons de ceux-ci sur les plate-formes. Dans le cas le plus complexe, où tous les actionneurs et toutes les liaisons seraient différents, le nombre de données à mémoriser est de 4 par actionneur (longueur minimum, longueur maximum, angle maximum de pivotement de sa liaison de base, angle maximum de pivotement de sa liaison de tête), soit pour l'ensemble du robot: 24 n (où n est le nombre d'étage).Furthermore, according to a first embodiment, the storage means 26 comprise memories containing data representative of the possibilities of movement of the different components used: actuators and links thereof on the platforms. In the most complex case, where all the actuators and all the connections would be different, the number of data to be stored is 4 per actuator (minimum length, maximum length, maximum swivel angle of its basic link, maximum swivel angle of its head link), or for the whole robot: 24 n (where n is the number of stages).

Toutefois, en pratique, les actionneurs et liaisons d'un étage seront identiques entre eux, ce qui réduira à 4 le nombre de paramètres représentatifs de l'espace accessible de cet étage. De plus, certains étages peuvent être identiques et le nombre de données à mémoriser devient égal à 4 n′, où n′ ≦ n correspond au nombre de types différents d'étages. On conçoit donc qu'une telle mémorisation est très légère en espace mémoire nécessaire.However, in practice, the actuators and connections of a stage will be identical to each other, which will reduce to 4 the number of parameters representative of the accessible space of this stage. In addition, some stages may be identical and the number of data to be stored becomes equal to 4 n ′, where n ′ ≦ n corresponds to the number of different types of stages. It is therefore understandable that such storage is very light in memory space required.

Selon un autre mode de réalisation, les moyens de stockage 26 comprennent des mémoires contenant, pour chaque architecture d'étage, des relations liant les données d'espace accessible constituées en l'exemple, d'une quart, par les positions x, y, z du centre de la plate-forme par rapport à la plate-forme précédente, d'autre part, en chaque position, par la rotation possible α autour de toutes les directions de l'espace. Par rotation possible α, on entend pour une position donnée, la plus petite valeur parmi l'ensemble des angles de rotation maximum autour de toutes les directions. Ainsi, quelle que soit la direction de l'espace, la plate-forme est assurée de pouvoir tourner de cet angle α lorsqu'elle se trouve dans la position considérée.According to another embodiment, the storage means 26 comprise memories containing, for each floor architecture, relationships linking the accessible space data constituted in the example, by a quarter, by the positions x, y , z from the center of the platform with respect to the previous platform, on the other hand, in each position, by the possible rotation α around all the directions of space. By possible rotation α, is meant for a given position, the smallest value among the set of maximum rotation angles around all directions. Thus, whatever the direction of the space, the platform is guaranteed to be able to rotate by this angle α when it is in the position considered.

Pour un robot ayant des étages identiques, les espaces accessibles sont identiques pour toutes les plates-formes et peuvent être modélisés par des relations mathématiques entre les trois coordonnées de position x, y, z, et la rotation possible α, du type:
f (x, y, z, α) = 0

Figure imgb0001

For a robot with identical floors, the accessible spaces are identical for all the platforms and can be modeled by relations mathematics between the three position coordinates x, y, z, and the possible rotation α, of the type:
f (x, y, z, α) = 0
Figure imgb0001

Si les plates-formes ne sont pas identiques, sont mémorisées autant de relations de ce type qu'il y a de type de plate-forme.If the platforms are not identical, as many relationships of this type are memorized as there are types of platform.

La figure 8a est un diagramme donnant l'angle possible α en fonction de x, y et z. Cette famille de courbe obtenue point par point par le calcul présente une discontinuité et peut être modélisée par deux familles de droites telles que schématisées au diagramme de la figure 8b. Ces droites sont représentées par des équations du type précité et sont stockées dans les moyens 26 sous forme d'un programme de calcul apte à résoudre ces équations. (On peut constater que pour une altitude z optimum, les angles possibles α passent par un maximum).FIG. 8a is a diagram giving the possible angle α as a function of x, y and z. This family of curve obtained point by point by the calculation presents a discontinuity and can be modeled by two families of lines as shown diagrammatically in the diagram of figure 8b. These lines are represented by equations of the aforementioned type and are stored in the means 26 in the form of a calculation program capable of solving these equations. (We can see that for an optimum altitude z, the possible angles α go through a maximum).

Selon un autre mode de réalisation, les données d'espace accessible par chaque plate-forme sont stockées dans les moyens de stockage 26 sous la forme d'une base de données.According to another embodiment, the space data accessible by each platform are stored in the storage means 26 in the form of a database.

La figure 9a symbolise l'espace accessible, en position, par le centre d'une plate-forme par rapport à la plate-forme précédente. Les figures 9b, 9c et 9d sont des coupes horizontales de cet espace à différentes hauteurs, respectivement H₁, H₂, H₃.FIG. 9a symbolizes the space accessible, in position, through the center of a platform with respect to the previous platform. Figures 9b, 9c and 9d are horizontal sections of this space at different heights, H₁, H₂, H₃ respectively.

Cet espace accessible est découpé en un maillage à trois dimensions et, pour chaque noeud du maillage, est stocké un tableau, lui-même à trois dimensions, comme le schématise la figure 9b, relatif aux rotations possibles en ce noeud. A cet effet, de même que les positions sont discrétisées par le maillage, les rotations sont discrétisées par amplitudes (par exemple, degré par degré). Par exemple, dans un tableau affecté à un noeud donné, une case donnée correspond à trois valeurs discrètes d'angles de rotation prédéterminées (r₁, r₂, r₃) et contient une information en binaire de possibilité ou d'impossibilité de satisfaire la combinaison r₁, r₂, r₃ au noeud x, y, z. La base de données est préalablement établie par le calcul en établissant par un maillage conventionnel les noeuds et les tableaux correspondant et en testant la possibilité ou l'impossibilité pour chaque case de chaque tableau (compte-tenu des positions et orientations correspondant à ladite case), la base de donnée étant ensuite stockée dans les mémoires des moyens 26.This accessible space is divided into a three-dimensional mesh and, for each node of the mesh, a table, itself three-dimensional, is stored, as shown schematically in FIG. 9b, relating to the possible rotations at this node. For this purpose, just as the positions are discretized by the mesh, the rotations are discretized by amplitudes (for example, degree by degree). For example, in an array assigned to a given node, a given box corresponds to three discrete values of predetermined angles of rotation (r₁, r₂, r₃) and contains information in binary of possibility or impossibility of satisfying the combination r₁ , r₂, r₃ at node x, y, z. The database is previously established by the calculation by establishing by a conventional mesh the nodes and the tables corresponding and by testing the possibility or the impossibility for each box of each table (taking into account the positions and orientations corresponding to said box), the database then being stored in the memories of the means 26.

Ce stockage grâce à un maillage présente l'avantage de modéliser de façon plus réaliste l'espace accessible que la solution précédente (et donc de perdre moins de situations réellement accessibles), mais l'inconvénient d'être plus lourd en besoin de mémorisation et stratégie de vérification. Il faut souligner que la première solution est la plus performante car elle épouse de façon très étroite les réelles possibilités de mouvement des actionneurs.This storage thanks to a mesh has the advantage of modeling in a more realistic way the accessible space than the previous solution (and therefore of losing less really accessible situations), but the disadvantage of being heavier in need of memorization and verification strategy. It should be emphasized that the first solution is the most effective because it closely follows the real possibilities of movement of the actuators.

Les moyens de calcul de configuration 27 sont destinés à déterminer une configuration de robot (par l'ensemble des coordonnées généralisées: coordonnées d'un repère lié à chaque plate-forme par rapport à la plate-forme précédente ou à la base) dans laquelle le terminal se trouve dans la situation finale à atteindre (position, orientation).The configuration calculation means 27 are intended to determine a robot configuration (by the set of generalized coordinates: coordinates of a coordinate system linked to each platform with respect to the previous platform or to the base) in which the terminal is in the final situation to be reached (position, orientation).

Ces moyens de calcul de configuration constitués par un processeur de type connu en soi comprennent un programme de calcul itératif dont le logigramme est dessiné à la figure 10.These configuration calculation means constituted by a processor of a type known per se include an iterative calculation program, the flow diagram of which is drawn in FIG. 10.

Pour démarrer le calcul itératif, ces moyens de calcul font l'acquisition de la situation finale à atteindre par le terminal Xd (coordonnées opérationnelles saisies: position, orientation) et d'une situation initiale X dudit terminal. Cette dernière peut être représentée par des coordonnées arbitraires préalablement stockées dans une mémoire auxiliaire du processeur ou par des coordonnées calculées au cours d'une étape préalable à partir des signaux issus des capteurs (représentant alors la configuration réelle du robot à l'instant considéré); dans ce dernier cas, le processeur est doté d'un organe de calcul auxiliaire qui est apte à fournir les coordonnées opérationnelles correspondant à une configuration donnée.To start iterative calculation, these calculation means acquire the final situation to be reached by the terminal Xd (operational coordinates entered: position, orientation) and an initial situation X of said terminal. The latter can be represented by arbitrary coordinates previously stored in an auxiliary memory of the processor or by coordinates calculated during a prior step from signals from the sensors (then representing the real configuration of the robot at the instant considered) ; in the latter case, the processor is provided with an auxiliary calculation unit which is capable of providing the operational coordinates corresponding to a given configuration.

La première opération de calcul itératif consiste à calculer la distance mathématique d entre la situation finale et la situation initiale préalablement acquises. Cette distance est déterminée par un calcul vectoriel, terme à terme.The first iterative calculation operation consists in calculating the mathematical distance d between the final situation and the initial situation previously acquired. This distance is determined by a calculation vector, term to term.

On teste si la distance obtenue est ou non inférieure à un écart prédéterminé -e- (comparaison de la norme de la distance par rapport au scalaire -e-). Dans l'affirmative, le processus s'arrête, puisque la configuration du robot (soit initiale, soit calculée à l'étape précédente) constitue la solution (à l'écart -e- près admis).We test whether or not the distance obtained is less than a predetermined deviation -e- (comparison of the norm of the distance with respect to the scalar -e-). If so, the process stops, since the robot configuration (either initial or calculated in the previous step) constitutes the solution (apart from -e- allowed).

Dans la négative, on calcule la matrice Jacobienne de déplacement [J] correspondant à la configuration initiale ou à la configuration obtenue à l'étape précédente.If not, the Jacobian displacement matrix [J] is calculated corresponding to the initial configuration or to the configuration obtained in the previous step.

Comme connu, la matrice Jacobienne de déplacement est constituée de termes représentant chacun la dérivée première des coordonnées opérationnelles par rapport à chacune des coordonnées généralisées de tous les étages. Le terme i, j, de cette matrice Jacobienne est ainsi égal à ∂f i ∂d j

Figure imgb0002
, où f est la relation liant les coordonnées généralisées notées q aux coordonnées opérationnelles notées x: x = f (q),As known, the Jacobian displacement matrix consists of terms each representing the first derivative of the operational coordinates with respect to each of the generalized coordinates of all the stages. The term i, j, of this Jacobian matrix is thus equal to ∂f i ∂d j
Figure imgb0002
 , where f is the relation linking the generalized coordinates noted q to the operational coordinates noted x : x = f ( q ),

i variant de 1 à n, où n est le nombre de coordonnées opérationnelles représentatives d'une situation finale,i varying from 1 to n, where n is the number of operational coordinates representative of a final situation,

j variant de 1 à m, où m est le nombre total de coordonnées généralisées représentatives d'une configuration du robot.j varying from 1 to m, where m is the total number of generalized coordinates representative of a configuration of the robot.

On exécute ensuite deux opérations logiques sur la matrice Jacobienne: en premier lieu, une opération d'inversion de la matrice Jacobienne suivant un critère prééatabli, ensuite une opération de multiplication de la matrice inversée [Jinv] par la distance d ou une fraction de celle-ci (r.d).We then execute two logical operations on the Jacobian matrix: first, an inversion operation of the Jacobian matrix according to a pre-established criterion, then an operation of multiplication of the inverted matrix [Jinv] by the distance d or a fraction of that -ci (r. d ).

On sait que l'inversion d'une matrice Jacobienne rectangulaire (non carrée) conduit à plusieurs solutions et le critère préétabli permet d'en choisir une. En particulier, ce choix peut être effectué de façon à minimiser la norme euclidienne des incréments des coordonnées généralisées de tous les étages. La matrice inversée est alors la matrice connue sous le nom de "pseudo-inverse de Moore-Penrose". Ce choix conduit à minimiser à chaque étape le déplacement de chaque plate-forme. Bien entendu, d'autres critères de choix d'inverse peuvent être utilisés, tendant par exemple à favoriser le déplacement des étages supérieurs par rapport à ceux proches du socle (afin de réduire les masses déplacées). (On pourra se reporter à la publication suivante, fournissant tout détail sur les matrices Jacobiennes et leurs inverses: "Génération de mouvements en robotique. Application des inverses généralisées A. FOURNIER, Thèse de Doct. d'état, 1980 MONTPELLIER").We know that the inversion of a rectangular (not square) Jacobian matrix leads to several solutions and the pre-established criterion allows one to be chosen. In particular, this choice can be made so as to minimize the Euclidean norm of the increments of the generalized coordinates of all the stages. The inverted matrix is then the matrix known as the "Moore-Penrose pseudo-inverse". This choice leads to minimizing the displacement of each platform at each stage. Of course, other inverse choice criteria can be used, tending for example to favor the displacement of the upper floors by compared to those close to the base (in order to reduce the displaced masses). (We can refer to the following publication, providing all details on Jacobian matrices and their inverses: "Generation of movements in robotics. Application of generalized inverses A. FOURNIER, Doctoral thesis, 1980 MONTPELLIER").

L'opération de multiplication avec la distance ou une fraction de celle-ci fournit un ensemble d'incréments [Jinv] (r.d) qui sont ensuite ajoutés aux coordonnées généralisées q représentant la configuration du robot à l'étape précédente pour obtenir de nouvelles coordonnées généralisées représentant la nouvelle configuration de robot.The multiplication with distance or a fraction thereof provides a set of increments [Jinv] (r. D ) which are then added to the generalized coordinates q representing the configuration of the robot in the previous step to obtain new generalized coordinates representing the new robot configuration.

Lorsque la distance d est grande, il est souhaitable d'opérer la multiplication par une fraction (r.d) (r  <  1) de cette distance, afin d'obtenir une convergence non oscillante. Ce coefficient peut être modifié en fonction de la distance à chaque itération.When the distance d is large, it is desirable to operate the multiplication by a fraction (r. D ) (r <1) of this distance, in order to obtain a non-oscillating convergence. This coefficient can be modified according to the distance at each iteration.

Les simulations ont montré que cette procédure itérative utilisant la matrice Jacobienne permet une convergence relativement rapide et fiable vers la situation finale à atteindre par le terminal.The simulations have shown that this iterative procedure using the Jacobian matrix allows a relatively fast and reliable convergence towards the final situation to be reached by the terminal.

La procédure itérative se poursuit par un test de vérification d'appartenance des situations représentées par les coordonnées généralisées obtenues, avec les situations accessibles représentées par les données d'espace accessible stockées dans les moyens de stockage 26.The iterative procedure continues with a verification test of membership of the situations represented by the generalized coordinates obtained, with the accessible situations represented by the accessible space data stored in the storage means 26.

En cas d'appartenance des situations calculées à l'ensemble des situations accessibles, on valide la nouvelle configuration pour passer à l'étape suivante de calcul.If the calculated situations belong to all of the accessible situations, the new configuration is validated to go to the next calculation step.

En cas de non-appartenance, on substitue à chaque situation calculée inadmissible une situation accessible proche, choisie suivant un critère préétabli. Par exemple, en se reportant au diagramme des situations accessibles de la figure 8b, si l'on suppose que la situation non accessible d'une plate-forme est représentée par le point P (p, Zp, tp), le critère de substitution peut consister à rechercher une situation accessible, d'abord en modifiant -t-, puis si nécessaire en modifiant Z, enfin, si nécessaire, en modifiant α. Dans le cas du point P, on modifie d'abord la valeur -t- pour lui donner une valeur 0, puis on modifie l'ordonnée Z jusqu'au point P′ où l'on atteint une situation accessible (p, Zp′, O). Ce critère de substitution privilégie les rotations. Bien entendu, d'autres critères peuvent être utilisés selon l'application.In the event of non-membership, one substitutes for each calculated inadmissible situation a nearby accessible situation, chosen according to a pre-established criterion. For example, referring to the diagram of accessible situations in Figure 8b, if we assume that the non-accessible situation of a platform is represented by the point P (p, Zp, tp), the substitution criterion may consist in seeking an accessible situation, first by modifying -t-, then if necessary modifying Z, finally, if necessary, modifying α. In the case of point P, we first modify the value -t- to give it a value 0, then we modify the ordinate Z up to point P ′ where we reach an accessible situation (p, Zp ′ , O). This substitution criterion favors rotations. Of course, other criteria can be used depending on the application.

Par exemple, le logigramme de la figure 11 illustre un programme particulier de mise en oeuvre des opérations op de vérification et de substitution (mises en évidence dans un cadre discontinu à la figure 10). Ce logigramme se rapporte au cas où est stockée dans les moyens de mémorisation une base de données contenant pour chaque vérin les longueurs, minimale et maximale, et angles maximum de pivotement par rapport aux normales aux deux plate-formes voisines.For example, the flow diagram in FIG. 11 illustrates a particular program for implementing the operations of verification and substitution op (highlighted in a discontinuous frame in FIG. 10). This flowchart relates to the case where a database is stored in the storage means containing for each cylinder the lengths, minimum and maximum, and maximum angles of pivoting with respect to the norms at the two neighboring platforms.

A partir de la configuration calculée (point A des logigrammes), c'est-à-dire des coordonnées généralisées de chaque étage, on effectue le calcul des longueurs correspondantes 1i des 6 vérins de chaque étage (calcul vectoriel traditionnel).From the calculated configuration (point A of the flow diagrams), that is to say the generalized coordinates of each stage, the corresponding lengths 1i of the 6 cylinders of each stage are calculated (traditional vectorial calculation).

Un test sur chaque longueur 1i ainsi calculée est réalisé: si l'une des longueurs 1i se trouve en dehors de la plage longueur minimale ― longueur maximale (sortie: non), l'on met en oeuvre un programme de substitution consistant à faire varier de façon homothétique toutes les longueurs calculées en vue de ramener les valeurs de dépassement à l'intérieur de la plage autorisée.A test on each length 1i thus calculated is carried out: if one of the lengths 1i is outside the range minimum length - maximum length (output: no), a substitution program is implemented which consists in varying homothetically all the lengths calculated in order to bring the overshoot values within the authorized range.

A partir des nouvelles longueurs ainsi définies, on calcule les nouvelles coordonnées généralisées pour l'étage considéré (calcul itératif classique faisant intervenir une matrice Jacobienne carrée).From the new lengths thus defined, the new generalized coordinates for the stage considered are calculated (classic iterative calculation involving a square Jacobian matrix).

Au point B du logigramme, L'on dispose des coordonnées généralisées de chaque étage (soit directes, soit substituées) et l'on effectue le calcul des deux angles γi que l'axe de chaque vérin forme avec les normales aux deux plate-formes contiguës (calcul trigonométrique traditionnel).At point B of the flowchart, we have the generalized coordinates of each stage (either direct or substituted) and we perform the calculation of the two angles γi that the axis of each cylinder forms with the normals to the two platforms contiguous (traditional trigonometric calculation).

Un test sur chaque angle γi ainsi calculé est réalisé: si l'un des angles γi dépasse la valeur maximale (sortie: non), l'on met en oeuvre un programme de substitution par approximations successives (méthode de dichotomie); ce programme consiste à réduire les longueurs 1i dans un rapport donné par rapport à une longueur moyenne, puis à calculer les angles γi correspondants et à refaire le test de non-dépassement, ces opérations étant répétées jusqu'à ce que les angles calculés deviennent au plus égal aux valeurs maximales admissibles.A test on each angle γi thus calculated is carried out: if one of the angles γi exceeds the maximum value (exit: no), a substitution program by successive approximations is implemented (dichotomy method); this program consists in reducing the lengths 1i in a given ratio compared to an average length, then in calculating the corresponding angles γi and in redoing the non-overshoot test, these operations being repeated until the angles calculated become at plus equal to the maximum allowable values.

A cet instant, l'on calcule les coordonnées généralisées de l'étage qui serviront au calcul de la nouvelle situation du terminal pour l'itération considérée. Ce calcul fournit ainsi une configuration de robot, pour laquelle toutes les situations de plate-forme sont accessibles. La figure 12 illustre les configurations du robot, aux étapes d'itération k-1 et k.At this instant, the generalized coordinates of the floor are calculated which will be used to calculate the new situation of the terminal for the iteration considered. This calculation thus provides a robot configuration, for which all platform situations are accessible. FIG. 12 illustrates the configurations of the robot, in the iteration steps k-1 and k.

A partir de la nouvelle configuration ainsi calculée (directe ou substituée), l'on détermine les coordonnées opérationnelles correspondantes du terminal.From the new configuration thus calculated (direct or substituted), the corresponding operational coordinates of the terminal are determined.

Cette détermination s'effectue par un calcul géométrique consistant à calculer les coordonnées opérationnelles du terminal (par rapport à un repère lié au socle) à partir des coordonnées généralisées de tous les étages (ensemble des coordonnées de chaque plate-forme dans un repère lié à chaque plate-forme précédente). Ce calcul classique utilise en particulier des matrices de passage d'un repère lié à un étage à un autre lié à l'étage précédent pour calculer de proche en proche les coordonnées absolues des plates-formes depuis la base jusqu'au terminal.This determination is made by a geometric calculation consisting in calculating the operational coordinates of the terminal (relative to a reference frame linked to the base) from the generalized coordinates of all the floors (set of coordinates of each platform in a reference frame linked to each previous platform). This conventional calculation in particular uses matrices for passing from a reference linked to one stage to another linked to the preceding stage to calculate step by step the absolute coordinates of the platforms from the base to the terminal.

A partir de ces nouvelles coordonnées opérationnelles, on calcule une nouvelle distance d = Xd  -  X en vue d'une nouvelle étape itérative, comme l'illustre la boucle du logigramme de la figure 10.From these new operational coordinates, a new distance d = Xd - X is calculated with a view to a new iterative step, as illustrated by the loop in the flow diagram of FIG. 10.

Les moyens de calcul de configuration 27 comprennent un compteur d'étapes itératives afin d'arrêter le processus lorsqu'un nombre déterminé d'itérations est atteint sans obtention du résultat (c'est-à-dire d  <  e). En pratique, ce nombre sera fonction de l'application et de la précision -e- désirée (de l'ordre de 10 à 50). On estime alors que la situation à atteindre par le terminal est en dehors du domaine accessible du robot.The configuration calculation means 27 comprise a counter of iterative steps in order to stop the process when a determined number of iterations is reached without obtaining the result (that is to say d <e). In practice, this number will depend on the application and the precision -e- desired (of the order of 10 to 50). It is then estimated that the situation to be reached by the terminal is outside the domain accessible from the robot.

Pour chaque étage, les coordonnées généralisées obtenues à l'issue du calcul itératif sont délivrées vers les moyens de calcul d'états 28, qui les transforment, pour chaque actionneur de l'étage considéré, en informations d'états représentatives de l'état que doivent prendre ces actionneurs pour disposer l'étage considéré dans la situation calculée qui lui correspond.For each stage, the generalized coordinates obtained at the end of the iterative calculation are delivered to the state calculation means 28, which transform them, for each actuator of the stage considered, into state information representative of the state that these actuators must take to arrange the stage considered in the calculated situation which corresponds to it.

La situation de la plate-forme de chaque étage étant connue par rapport à la plate-forme précédente (position, orientation), le calcul des états consiste en un calcul géométrique des longueurs entre points d'articulations des actionneurs.The situation of the platform of each stage being known with respect to the previous platform (position, orientation), the calculation of the states consists in a geometric calculation of the lengths between points of articulations of the actuators.

Les moyens de calcul d'états délivrent pour chaque étage six scalaires représentatifs desdites longueurs entre points d'articulations, vers l'interface d'asservissement 30. Cette dernière, qui peut être de type classique "P.I.D." (commande "proportionnelle, intégrale, dérivée"), est soit numérique, soit analogique avec conversion.The state calculation means deliver for each stage six scalars representative of said lengths between points of articulations, towards the servo interface 30. The latter, which can be of the conventional "P.I.D." type ("proportional, integral, derivative" command), is either digital or analog with conversion.

A la fin des rotations des moteurs électriques des actionneurs, le robot prend physiquement la forme de la configuration calculée.At the end of the rotations of the electric motors of the actuators, the robot physically takes the form of the calculated configuration.

Les longueurs des actionneurs, qui correspondent à des situations finales de terminal spécifiques, peuvent être mémorisées dans les moyens 29 de mémorisation d'états, afin d'effectuer des tâches répétitives sans refaire les calculs de configuration, les informations d'états étant alors injectées directement dans l'interface d'asservissement 30.The lengths of the actuators, which correspond to specific final terminal situations, can be stored in the state storage means 29, in order to perform repetitive tasks without redoing the configuration calculations, the state information then being injected directly in the servo interface 30.

Par ailleurs, la figure 13 présente une variante architecturale de robot, dans laquelle chaque plate-forme 33 est formée par une couronne (treillis ou couronne pleine) dotée de trois zones en saillie du côté supérieur et de trois zones en saillie du côté inférieur. Ces zones sont angulairement décalées de 60°. Les zones en saillie supérieures portent chacune l'articulation de deux actionneurs de l'étage, cependant que les zones en saillie inférieures portent chacune l'articulation de deux actionneurs de l'étage suivant.Furthermore, FIG. 13 presents an architectural variant of a robot, in which each platform 33 is formed by a crown (trellis or solid crown) provided with three projecting zones on the upper side and three projecting zones on the lower side. These areas are angularly offset by 60 °. The upper protruding zones each carry the articulation of two actuators of the stage, while the lower protruding zones each carry the articulation of two actuators of the stage following.

On obtient ainsi une structure où les étages s'interpénètrent, donc plus compacte. Toutefois, cet avantage s'obtient au prix de contraintes en flexion dans les plates-formes.We thus obtain a structure where the floors interpenetrate, therefore more compact. However, this advantage is obtained at the cost of bending stresses in the platforms.

La figure 14 illustre un autre mode de réalisation de robot, qui se différencie des précédents par la forme allongée des plates-formes, les autres caractéristiques étant identiques. Chaque plate-forme 34 est constituée par une membrure rigide allongée: cylindre tubulaire ou treillis. Les actionneurs d'un étage sont articulés sur une extrémité 34a de la plate-forme de l'étage considéré, les actionneurs de l'étage suivant étant articulés sur l'extrémité opposée 34b de ladite plate-forme.FIG. 14 illustrates another embodiment of the robot, which differs from the previous ones by the elongated shape of the platforms, the other characteristics being identical. Each platform 34 is constituted by an elongated rigid member: tubular cylinder or lattice. The actuators of a stage are articulated on one end 34a of the platform of the stage in question, the actuators of the following stage being articulated on the opposite end 34b of said platform.

Un tel robot est apte à couvrir un domaine très étendu eu égard au nombre d'étages, mais au prix d'un espace de travail du robot plus limité à proximité immédiate de la base.Such a robot is able to cover a very large area having regard to the number of stages, but at the cost of a more limited robot workspace in the immediate vicinity of the base.

La figure 15 illustre une autre variante dans laquelle des étages auxiliaires tels que 35 sont interposés entre étages modulaires déjà décrits du robot.FIG. 15 illustrates another variant in which auxiliary stages such as 35 are interposed between already described modular stages of the robot.

Chaque étage auxiliaire présente une géométrie analogue à celle des étages modulaires, mais deux, trois ou quatre actionneurs sont remplacés par des barres rigides telles que 36, de façon à obtenir une structure isostatique angulée fermée à six éléments. Dans l'exemple dessiné, ces six éléments sont formés par quatre actionneurs et deux barres rigides.Each auxiliary stage has a geometry similar to that of the modular stages, but two, three or four actuators are replaced by rigid bars such as 36, so as to obtain an angular closed isostatic structure with six elements. In the example drawn, these six elements are formed by four actuators and two rigid bars.

La longueur des barres rigides 36 est choisie en rapport avec celle (minimale ou maximale) des actionneurs afin de décaler l'emplacement de l'espace de travail du robot vers tel ou tel secteur.The length of the rigid bars 36 is chosen in relation to that (minimum or maximum) of the actuators in order to shift the location of the working space of the robot towards such or such sector.

Un tel robot est intéressant dans certaines applications où une très grande redondance serait superflue, car il permet de réduire le coût de la structure et celui de la commande (en raison du nombre d'actionneurs réduit), tout en conservant la géométrie triangulée de la structure et les avantages inhérents à celle-ci (grande légèreté vis-à-vis des charges admissibles).Such a robot is interesting in certain applications where very great redundancy would be superfluous, because it makes it possible to reduce the cost of the structure and that of the control (due to the reduced number of actuators), while retaining the triangulated geometry of the structure and the advantages inherent in it (great lightness vis-à-vis the admissible loads).

Claims (23)

1. A robot permitting displacement of a terminal (7) from an initial position to a final position, of a redundant and modular type comprising at least two stages arranged one after another, of which a first stage is fixed to a base and the opposite thereto, a last stage carries the terminal, each stage (1i) comprising a platform (2) and six linear actuators (3a-3f), each articulated at one extremity, on the platform of the stage considered by a ball-and-socket connection, and at its opposite extremity, on the platform of the preceding stage (or on the base for the first stage) by a connection of the same type, these six linear actuators being arranged according to a closed angular architecture of a type in which two adjacent actuators are articulated in the vicinity of each other to one platform and on the contrary are articulated to another platform at a distance from each other in order to form an angle between them, each stage comprising a system of sensors (4a-4c), adapted to deliver signals representative of the relative position of the platform of said stage with respect to that of the preceding stage (or with respect to the base for the first stage),
said robot being characterized in that it comprises a control unit associated with the actuators, comprising:
data storage means (26), termed accessible space data, representative of accessible positions for each platform in a reference system connected to the preceding stage (or to the base for the first stage),
means (25) for inputting the operational coordinates representative of the final position to be attained,
computing means (27), termed configuration computing means, arranged to enter into the storage means (26) the accessible space data and for receiving the operational coordinates from the inputting means (25), said configuration computing means containing a program for iterative calculations according to the following procedure:
computing the distance between the position of the terminal corresponding to the configuration obtained in the preceding stage and the final desired position,
computing the Jacobian displacement matrix associated with the configuration obtained in the preceding stage,
executing logical operations between the Jacobian matrix and the distance for determining a new position of the platform, the totality of said positions being representative of a new configuration of the robot,
verifying the suitability of these positions with the accessible positions for each platform and, in case of unsuitability, substituting for the calculated position an accessible position,
determining the position of the terminal corresponding to the new configuration,
repeating this procedure until obtaining a distance between the final position and the last calculated position of the terminal which is less than a predetermined variation for determining a configuration of the robot for which the terminal (7) is situated in the final position and for delivering the generalized coordinates representative of said configuration or an information of impossibility,
calculating means (28), termed status calculating means, arranged to receive the generalized coordinates representative of the configuration of the robot and adapted to compute, for each stage, the corresponding status data of the six linear actuators,
an operating mechanism interface (30) arranged to receive the status data from the state computing means (28) as well as the signals from the sensor system (4a, 4c) and adapted to deliver the proper magnitudes of control to control each of the linear actuators.
2. A robot as in Claim 1, characterized in that the accessible space data storage means comprises memory means, storing for each architecture of stages a database containing for each actuator of the stage considered, the minimum and maximum lengths of this actuator and the maximum angles which may be made by said actuator with respect to normals to the two platforms to which said actuator is connected.
3. A robot as in Claim 1, characterized in that the accessible space data storage means comprises means for storing a computing program, containing for each architecture of the stage, the relationships connecting the position (x, y, z) of the center of the platform of the stage with respect to the adjacent platform and the possible rotation (α) of said platform following all the directions in space.
4. A robot as in Claim 1, characterized in that accessible space data storage means (26) comprises memorizing means for storing, for each architecture of stages, a database divided into zones corresponding to the nodes of a spatial network, each zone containing data representative of the position of the corresponding node (x, y, z) and the digitized rotations for this node in predetermined directions (r₁, r₂, r₃).
5. A robot as in one of Claims 1 to 4, characterized in that the means (25) for inputting the operational coordinates representative of the final position to be attained comprises a man/machine interface (31) adapted to permit input of tbe coordinates representative of the final spatial position to be attained for a given point connected to the terminal and/or the coordinates representative of the final orientation to be attained for said terminal.
6. A robot as in one of Claims 1 to 4, characterized in that the inputting means (25) for the operational coordinates representative of the final position to be attained comprises a remote sensing camera (24) adapted to detect a target to be reached, and treatment means (32) adapted to deliver from the signals coming from the remote sensing camera the coordinates representative of the spatial position and/or the spatial orientation of the target in a reference connected to the camera.
7. A robot as in one of Claims 5 or 6, characterized in that the inputting means (25) comprises a sub-assembly (25a) for conversion of the coordinates, adapted to transform the coordinates from the treatment means (32) into operational coordinates with respect to a reference system connected to the base of the robot.
8. A robot as in one of the preceding claims, characterized in that the configuration computing means (27) contains a program in which the logical operations between the Jacobian matrix and the distance consist successively of executing an inversion operation of the Jacobian matrix following a pre-established criterion, executing a multiplication of the inverted matrix by the distance in order to obtain an assembly of increments, and executing an addition operation of said increments to the generalized coordinates corresponding to the preceding configuration for obtaining the generalized coordinates of the new configuration.
9. A robot as in Claims 2, characterized in that the configuration computing means (27) contains a program for verification of the suitability consisting of, at each iteration, computing for the new configuration of each stage, the length of the actuators and their angles with respect to the normals to the platforms, and comparing these lengths and angles to those contained in the accessible space storage means for detecting the excess values.
10. A robot as in one of the preceding claims, characterized in that the configuration computing means (27) contains a substitution program in which the substitution operates in case of non-appurtenance of a computed position of the assembly of accessible positions for a predetermined platform, consisting of computing the generalized coordinates representative of the closest accessible position following a preestablished criterion and substituting these coordinates to those computed for said platform.
11. A robot as in Claims 9 and 10 taken together, characterized in that the configuration computing means (27) comprises a substitution program consisting in case of an exceeded value of causing a variation in a homothetic manner of the lengths and angles of the actuators of the stage concerned for bringing the value or values exceeded within the authorized range, and computing the generalized coordinates of the resulting position.
12. A robot as in one of the preceding claims, in which the system of sensors (4a-4c) comprises a sensor mounted on each linear actuator, able to deliver a signal representative of the length of said actuator.
13. A robot as in one of the preceding claims, in which the six actuators (3a, 3f) of each stage are articulated to the platform (2) of the stage considered in three distinct zones of said platform, and on the platform of the preceding stage (or on the base for the first stage) in three distinct zones of said platform (or of said base).
14. A robot as in Claim 13, in which the six actuators (3a, 3f) of each stage are identical, the three zones of articulation of the actuators on the platform of the stage considered and the three zones of articulation of said actuators on the platform of the preceding stage being arranged at the apices of equilateral triangles.
15. A robot as in one of claims 13 or 14 characterized in that, on a given platform, the three zones of articulation of the actuators of the corresponding stage are approximately superimposed with the three zones of articulation of the actuators of the following stage.
16. A robot as in Claim 15, characterized in that each platform comprises three articulation blocks (8a, 8b, 8c) connected by cross-members in a triangle (9a, 9b, 9c), each articulation block being adapted to receive the connections of a ball-and-socket type of four linear actuators belonging to two stages situated above and below the platform considered.
17. A robot as in one of Claims 13 or 14, characterized in that on a given platform (33), the three zones of articulation of the actuators of the corresponding stage are angularly spaced by 60° with respect to the three zones of articulation of the actuators of the following stage.
18. A robot as in one of Claims 13 or 14, characterized in that at least one platform comprises a rigid member of elongated form (34), the actuators of the stage concerned being articulated to an extremity (34a) of said member, and the actuators of the following stage being articulated to the opposite extremity (34b) of said member.
19. A robot as in one of Claims 13, 14 or 17, characterized in that it comprises auxiliary stages (35) interposed between said stages, termed modular stages, each auxiliary stage being composed of a platform of two, three or four linear actuators and a complementary number of rigid bars (36), in such a manner as to obtain a closed angular isostatic structure of six elements having a geometry analogous to that of a modular stage.
20. A robot as in one of the preceding claims, characterized in that each platform (2) is hollow in its central zone so as to preserve a central passage running along the robot for housing a transmission network (feed and control of the actuator, transmission of signals from the sensors, and eventually feed and control of an active terminal).
21. A robot as in one of the preceding claims, characterized in that each platform comprises two plates (37, 38) assembled one on the other, for producing a module composed of a lower plate, six actuators, a system of sensors, and an upper plate.
22. A robot as in one of the preceding claims, characterized in that each linear actuator is articulated by a universal joint (22) at its extremities to the platform of the corresponding stage and to that of the preceding stage, each actuator being of a type adapted to permit a rotation about its longitudinal axis.
23. A robot as in one of the preceding claims, in which each linear actuator comprises a casing (19) connected to a nut (18), articulated at its extremity to a platform, a screw (17) threaded into said screw, a housing (15) containing said screw in such a manner as to permit its free rotation, and an electric motor (14) carried by said housing and arranged to rotate said screw, the housing (15) being articulated on the other platform.
EP88901269A 1987-02-04 1988-01-19 Redundant robot Expired - Lifetime EP0344185B1 (en)

Priority Applications (1)

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AT88901269T ATE67710T1 (en) 1987-02-04 1988-01-19 MODULAR ROBOT WITH UNNECESSARY DEGREE OF FREEDOM.

Applications Claiming Priority (2)

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FR8701884 1987-02-04
FR8701884A FR2610236B1 (en) 1987-02-04 1987-02-04 MODULAR TYPE REDUNDANT ROBOT

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EP0344185A1 EP0344185A1 (en) 1989-12-06
EP0344185B1 true EP0344185B1 (en) 1991-09-25

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EP (1) EP0344185B1 (en)
AT (1) ATE67710T1 (en)
DE (1) DE3865196D1 (en)
ES (1) ES2006544A6 (en)
FR (1) FR2610236B1 (en)
WO (1) WO1988005712A1 (en)

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WO1988005712A1 (en) 1988-08-11
DE3865196D1 (en) 1991-10-31
FR2610236B1 (en) 1991-07-12
EP0344185A1 (en) 1989-12-06
ATE67710T1 (en) 1991-10-15
ES2006544A6 (en) 1989-05-01
FR2610236A1 (en) 1988-08-05

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